Except it doesn't work quite right. My friend and I both have iPhones and iPads. If I send her a "text" from my iPhone, sometimes it ends up on her iPad, if the last place she sent me a message was from her iPad, and vice versa. This results in missed messages both ways. If iMessage delivers a message, it should deliver to all registered devices for the user. The process is so opaque that you can't really see what it's doing to try to get it to work right. In that sense, it's kind of like Siri, the concept is the right one, but the execution sucks.