It's now possible to upload your position to aprs.fi from Google Latitude. Latitude, in turn, supports uploading position from a large number of mobile devices (Android, iPhone, Blackberry, Nokia/Symbian, Windows Mobile) using Google's Maps and Latitude applications.
See the user guide section on Google Latitude support for instructions.
If you don't see your position immediately on aprs.fi, please wait for a few minutes, and check if Google Latitude has your position on it's own web site. If it isn't shown there, the problem lies with your mobile application's configuration or lack of accurate position information on the phone. aprs.fi currently rejects positions with an accuracy that is worse than 4000 meters.
The web stations page in the user guide is a new thing, too. In addition to Latitude support, it documents the manual updating (point-and-click) and Geolocation API (web browser with GPS support on a mobile device) methods for position updating.
Feedback welcome, as usual!