Apple Inc. has now published on its website the procedure for activating for owners iPhone 4, iPad or iPod touch 4th generation service Find My iPhone free. You can find everything at to the following address. Then just go to iOS 4.2 at 19:00 and you can start using Find My iPhone
It's a shame it doesn't support 3Gs, I'd say most owners have it iPhone :)
Functional, I like it :) And it's great :)
Laqos – it's clear from the article and you mean it right, but I'd better say it again: it works on the 3GS as part of a paid service, it's not free yet.