Well, this is what's become of dodgeball...the original group location awareness platform that Google acquired a while back.
According to Google, Latitude is a feature of Google Maps for mobile on these phones:
* Android-powered devices, such as the T-Mobile G1
* iPhone and iPod touch devices (coming soon)
* most color BlackBerry devices
* most Windows Mobile 5.0+ devices
* most Symbian S60 devices (Nokia smartphones)
* many Java-enabled (J2ME) mobile phones, such as Sony Ericsson devices (coming soon)