How I wish all my communications could be funneled into just one channel: e-mail, chats on different media, even phone calls, etc. All registered in just one app so it stays coherent and I don't have to browse 7 apps when I'm looking for something. It's far more of a legal problem than a technical one, and it's a *shame*.
There used to be something like that for IM called Meebo. It's a great idea, but do chat systems like Facebook allow third party apps?
I don't see anything changing until messaging services are compelled by law to interoperate with 3rd party apps. This mess is there to last.