In the future, your boss will always know exactly where you are. But why wait; sign on to Loopt, recruit your boss to do the same, and you're already living in Tomorrowland. Loopt is a location-aware social networking app--it uses the GPS chip in your 3G iPhone (or more crudely, with the cell tower location data in the first generation iPhone) to place you on a map and to show you where your friends are and what they are up to. It's essentially a social network for the mobile set, allowing you to link up with friends and contacts and then mutually share location information.

The first step getting started using Loopt is adding friends--without any friends, the app isn't much use. Loopt can scan your iPhone's address book to look for existing users, much in the same way Facebook or Twitter can scrape your Gmail contacts when you first sign up on those sites, helping you build a network with existing users. Since Loopt already supports the BlackBerry and has Android support on the way, you can even use it to link up with friends on other mobile devices.

You can also manually enter phone numbers, or add contacts from your address book to send new invitations to expand the network, but these invitees will also have to download and install the application. It's worth noting, however, that these new user invites are sent not via e-mail, but by SMS text message. Many people find this annoying and it has caused a lot of controversy. Unlike e-mail, SMS messages are charged individually, so when you invite a friend via text message, you are, in fact, costing that person money, even if it's only a few cents. Loopt claims that it is up to the new user as to who gets an SMS invitation, and that a non-user can opt out of getting any additional invites. While both claims are true, SMS invites are still not a best practice. It's not always clear to new users that they are sending out cost-based (and some would argue annoying) text messages, nor should the burden be on non-users to opt out. Loopt should end this practice and provide an option to send invitations to new users via e-mail only.

However, once you have successfully annoyed your friends into joining Loopt, the app is actually fairly useful, even in its infancy, and promises to grow more so.

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