Lost, how is that much different than a phone? lol!
You can hide online status, and block people you don't like, which accually a phone company charges for :(  I use mainly msn, which asks before people can add you

And for the people who dis the new feature, I laugh, most any computer can already do exactly the same thing. The form of messenger means nothing, hell emails give the location it came from right on them. Oh dear I better quit using email! 

So ability has existed, only change is making it easier for "less edumicated" people to do it. To make it clear, tracing an IP to find a location is something that is about the level of "1st grade" to people who can program things to use on the net :)