For many, the decision will hinge on the features and functions. Heavy BlackBerry and Microsoft Outlook users, for instance, may default to the safety of hosted Exchange providers and their proven ability to effectively support both tools. And while Exchange is perfect for these and other customers, it's important to look beyond features and functions, to consider the total experience the providers wrap around their hosted services.

Hosted Exchange services are available from a mature ecosystem of partners delivering the service direct from their own data centers and, alternatively, directly from Microsoft. To be sure, there are substantial differences between the companies, but generally they have loads of experience.

Here are the major evaluation criteria to keep in mind when comparing hosted Exchange with Google Apps and why Exchange – particularly with hosted Exchange 2010 available – comes out on top:

* Ease of migrating your existing e-mail data, users, contacts and more. This is the biggest stumbling block for most organizations when evaluating hosted services. It's easier to stand pat than transition to a new service. A sophisticated hosted Exchange provider has been dealing with these issues for years. They will have a heavily automated (ideally free) migration process that ports all that you've invested in your existing e-mail set-up to the new environment. Take a minute to walk through Google's online sign up process, and it is clear the company's preferred mode of operation is "self serve".

* Certified 24x7 support for the tools your organization relies on – BlackBerry and Microsoft software. If your company organization relies heavily on Outlook and BlackBerry, and plans to continue doing so, good hosted Exchange providers can offer you the confidence that their support staff is Microsoft and RIM certified. Likewise, Outlook was designed to run over Exchange, not Google Apps.

* Business-Class Reliability. Solid hosted Exchange providers operate multiple data centers with redundancy and multiple Tier-1 Internet connections. They guarantee and deliver on 99.999% availability. That translates into less than six minutes of downtime per year. Google does not have that history with business users. With hosted Exchange 2010's architectural improvements, a good provider can also guarantee 100% data protection – never lose your e-mail – at no additional cost.

* Control over the environment. Many organizations considering migration to hosted communications tools will likely continue to use other Microsoft applications on-premise. Sophisticated hosted Exchange providers can offer single sign-on experience across these applications and other benefits that come by integrating with Exchange's Active Directory.

While some will argue that Google Apps is more cost effective, hosted options from either camp will result in massive cost savings vs. use of an on-premise server.

Considering the criteria outlined above, the most important question boils down to which service, in the larger picture, adds the right value to your business. For most businesses – particularly firms with knowledge workers and others heavily dependent on cutting-edge communications software – hosted Exchange is the right answer.

Gmail is, after all, one of the critical components of Google Apps, a suite that is already used by more than 1 million businesses. In fact, we can assume the growth of Google Apps is one of the main reasons Microsoft has bolstered its Business Productivity Online Standard Suite, which includes Exchange, SharePoint, Office Live Meeting and Office Communications.

But e-mail is the core of both suites, so we come back to comparing Gmail vs. Hosted Exchange.

Typically, the Exchange Camp will argue that the Gmail platform is not as full-featured, lacks support channels and doesn't support all mobile devices. Before we dive deeper into these half-truths, let's discuss one item the Exchange side won't argue: cost.

Gmail (and the entire Google Apps platform) costs much less on a per user basis then a comparable hosted Exchange 2010 solution. On average, hosted Exchange costs $141 per user per year compared with the $50 per user per year of Gmail. If you consider a larger organization with 500 users, on average a hosted Exchange Server will cost $45,780 more per year. In today's corporate environment, that is going to get the attention of any CFO.

I can hear the escalating cries from the Exchange Camp, "Cost is not the only deciding factor". Of course that's true. If it was the only thing we'd all be driving to work in our Yugos forcing down 25 cent coffee. Value has always been part of the purchasing equation and when you add it all up, there's lots of value in the Google story.

Consider the innovation factor. Last year Google added more than 40 new features for its Premier Edition Gmail users, in addition to the 45 new innovations released to its Docs and Sites applications. This in contrast to the hosted Exchange users who've waited up to three years to see a single new enhancement to the Exchange platform.

With the release of Exchange Server 2010, Managed Service Providers (MSP) are now scrambling to upgrade. Which means, of course, that hosted Exchange Server customers may be waiting awhile for their MSP to migrate them to the latest release. Even Microsoft's hosted Business Productivity Online Standard Suite (BPOS) is still running Exchange Server 2007, which illustrates the complexities involved.

Another criticism posited by the Exchange faithful is that of enterprise support. "What happens when a Gmail user has support issues? There's not even a support phone number!" That's weird, because I was just speaking with a Google Apps support representative by phone yesterday. Clicking on the support tab in my Google Apps control panel then dialing the 10 digits was exhausting and confusing, but I still managed to get through it.

All Google Apps Premier Edition customers have a support phone number for critical issues and escalation needs. In addition, there is a large online community and support site with reams of information regarding general questions about the service. Not to mention, the growing number of Google Apps MSPs that offer direct channels for phone and e-mail support.

One of primary knocks against Gmail for the enterprise is the lack of support for mobile devices, specifically BlackBerry. In reality, this claim is eroding fast if, in fact, it hasn't been completely washed away already.

Google's Gmail, calendar and contacts are available via a two-way sync with native applications or through installable applications on the majority of smartphones today. This includes the seamless integration with Google's own Android-based devices that are gaining momentum in the mobile market.

For RIM devices and the associated Blackberry Enterprise Server (BES), Google provides a connector for BES that allows BlackBerry users to utilize native applications for access to Google's Gmail, calendar and contact data. Google's Connector for BES also enables enterprise administrators to wipe remote devices the same way Exchange Server does.

While it's obvious Exchange Server and Outlook have tremendous market share in today's enterprises, there's no denying that Gmail and Google Apps provides a cost effective alternative, which more than 1 million businesses are benefiting from.

As Microsoft continues to do the heavy lifting required to push Exchange Server into the hosted landscape, Google continues to effortlessly roll out exciting innovations to Gmail and Apps. Considering the value, features, rate of innovation, ease of use and community support, no one will be surprised to see millions more make the exchange for Gmail and Google Apps.