Google Latitude is now available for the iPhone. Looks good too, the mobile web design they've done is second-to-none in my opinion, though there are a couple of odd niggles I saw, nothing that won't be fixed or a non-issue though.
For those who don't know, latitude is basically an awesome stalking app, which lets you see where your friends are and share your location with them. In theory great for coordinating meetups with friends, or seeing where the hot party is. Even better to use as a stalking app to find out where your ex-is now that the *sniff* bitch left *sniff* you for that bastard Ronnie!!