Google has released a Latitude application for the iOS platform (v4.0 or later) which means that all recent devices excluding the iPhone 3G and old iPod Touch that are powered by Apple's mobile operating system will be able to use the geolocation tracking service.
The opt-in location based service allows people to track (and be tracked by) others on a Google map and allows you to share one's location in the background and can be shared continuously with whomever the user chooses.
The level of control on one's privacy can also be changed; users can share at city-level lcoation, hide their location and turn off background updating whenever they want. You can find more about the application on iTunes here.
The launch on Latitude on the iOS platform will allow Google to exploit a user base of tens of millions of potential users, a move that comes as Google tries to open up the location based services market.
Latitude was launched back in February 2009 and was instantly a cause for concern amongst privacy groups worldwide.