Just installed the latest version of Google Maps onto my phone, hoping the Google Latitude function would work. I am able to log in - enable the 'Latitude' to show my location, but it doesn't seem to update the location.
From what I gather, this uses 'Triangulation' to figure out where you are (hence you don't need GPS).
Let me know if any of you are having better luck that me!
You can get the latest install at
http://www.google.com/latitude (connecting from you mobile gives you a download link)
Thanks!