Google have today announced the release of Google Latitude for the iPhone and iPod touch, available in the Safari browser.
To add Google Latitude visit google.com/latitude from your iPhone's browser. You can add a bookmark by opening Latitude in Safari and tapping the + icon > Add to Home Screen > Add.
Using Latitude in your iPhone lets you see the location of your friends on a Google Map. If you don't want to give too much away you can modify your privacy settings and control how your location is shared and with whom.
When you run the application in the foreground of your phone your location is continuously updated.
Via: Official Google Blog: Google Latitude on your iPhone