It's interesting, really. Steve Jobs at WWDC stated that the iPhone 2.0 was designed with business in mind - "you spoke, we listened".
But is AT&T on the same page? I wonder...
Office Reach, the ability to dial office extensions from a cell phone isn't offered on the iPhone. Note this isn't a device-specific feature, it just has to be allowed to be provisioned.
But here's the big one: There are "consumer" and "business" versions of the voice and data plans. Same minutes, same features, same data services (yes, Exchange push mail works with the consumer plan). The difference you ask? If you say you are using the iPhone for business, you get to pay $40 per month more for the same service.
The only other device I know of that has this price structure is the Blackberry - but the Blackberry requires specialized data access services like a BES and MDS. So is AT&T afraid of losing their BB base? Are they trying to get more revenue from iPhone users to offset BB loss?
Who knows, but a $480 per person per year premium for business users is outrageous.
I can tell you this: I probably use substantially LESS data as an Enterprise user compared to an application-loving, movie-watching college kid. If anything, I should be getting a discount.