Courtney
wrote up a little article on this new Android app called LiveProfile.
You can find it in the Market. Its basically an IM app similar to Blackberry Messenger. It uses PIN numbers like BBM and it lets you see when someone reads your message.
They're also coming out with a version for Blackberry and iPhone, so it'll be a cross-platform PIN-to-PIN messaging app. It doesn't support groups yet, but its planned in the future.
It also uses PUSH to save on battery. You can have a profile picture, update your status, set online/away modes, etc.
So, if you have it, what's your PIN number?
Mine is LPSXLS9C.