Twittermaps is a mashup that allows you to send posts about your current location.
According to the FAQ, just include the correct command and your current location will be viewable on the Twittermap.
eg. Going to the office. L:3000 6th Ave, New York.
What about getting the location of others.
eg. L steverubel
At the moment you can search the website to get this information via the search box, but what about on the go (and I don’t mean the mobile web, I mean SMS)…there’s also a search box here.
What about asking who of your friends and the people you follow are within 10 km radius of my location.
eg. get L…what about for the whole of Twitter, eg. getall L
[ADDED 19/03/07: Twittervision : real time map]