Google have released a native Lattitude application for the Apple iPhone so that iPhone owners can share GPS location even with the app closed.
Previously using Google's GPS friend tracker Lattitude required using a web application which was perfectly servicable but updates stopped if the user closed the application. Now, just like owners of Android handsets, Lattitude can send the user's GPS up to the Google cloud all the time.
Obviously there are significant privacy concerns with GPS tracking but Lattitude is an entirely opt-in service that requires friends and family to authorising tracking on a per user basis and can be easily permanently or temporarily disabled, or even reduce the accuracy to the city level.
Lattitude can be immensely handy, however. Wether it's parents that want to always know where their children are or if it's a bunch of mates finding eachother in bars down town, Lattitude is one of the truly great smartphone apps.
The Lattitude application works on the iPhone 3GS, iPhone 4, iPad, 3rd and 4th generation iPod touches but background tracking only works on the 3GS, 4 and iPad 3G.
Google produced a video showing the iPhone Lattitude app in action: