One of the best features of Apple's overpriced MobileMe service was Find My iPhone, which allows you to lock, send messages to, and remotely wipe your phone if you misplace it. And now, with the latest software update for the iPhone and iPad dropping today, it's free. Free!
This is great news, but not great news for MobileMe, which just lost its biggest selling point. But oh well! All you'll need to do to get the service working is to download the new software update and then grab the Find My iPhone app. Easy peasy.