You must log in with a google account and so your friends. It worked out good for me on long trips with my friends especially when they took a different route. I was able to keep track of them and their progress.
So if I get my wife and kids an Android 2.0 capable phone (which correct me if I am wrong but I think ALL 2.0 phones will have the cool mapping features that we have on our Droid), and they all have gmail accounts, can I actually see where they are at all times? I ask cause I was thinking..for my kids.. this would be great to have on their phones. I was paying verizon for a kid finder service a few years back with this green phone I got my daughter originally..but it was like $7 a month and would be a charge to find out where the phone was at each time I wanted to use it..or something like that..I never ended up using it. I am curious tho, if I get them all phones with 2.0, and enable this, if I can see where they are... how often does it update, what does it update (That is.. does each phone send a ping every so often to a google server that hosts this Lattitude service, which then stores a given phones location information)? How does my phone get updates to other phone locations.. does my phone ask a service (Lattitude) for info on given users all the time..or only if I run the Latitude app after firing up Maps?