I tried it out on my Blackberry curve. Works well. The bubble that pops up with a friend's picture and status is neat. Unfortunately only 2 friends have it installed. I had to zoom out to see both California and Colorado before I saw more than myself on the screen.
Reminds me of the time when I had to wear one of those bracelets as part of my parole.
Hmm, I can't imagine this working very well for the iPhone with no background application support, unless it makes it into the real Maps application and they provide an option to broadcast while it's not running.
This submission is from an official source (Google itself) and the headline mentions Loopt (a Y Combinator project), so I appreciate this addition to the discussion of this hot story.
There were lot of other start ups with similar services that are going to struggle due to this service. .