Google Latitude for iOS has been updated and it now supports iPhone 3G and improves battery usage.
Google Latitude lets you stay close with your friends from your phone, computer, or both.
* Find your friends on a map — see nearby friends and meet up.
* Share where you are with the friends you choose.
* Control your location and privacy.
What’s New In This Version:
* Improved battery usage
* Support for iPhone 3G (note that background location reporting is not supported by the hardware)
* Fixed bug where Maps button didn’t appear
* Location Services icon will no longer appear when not logged in
You can download Google Latitude from the App Store for free… but not available in Malaysia store, not sure about other countries.