Quote from xxcyylonexx
I REALLY doubt xbox gamers will be able to play with PC gamers. It has never happened in a game before so why now? It would mean less money for Microsoft because people wouldn't have to re-buy it to play with their xbox friends. If there was going to be cross-platform in that way, it probably wouldn't be for Minecraft.
I think by cross-platform they mean you will be able to share your skin or username between platforms.
Oh really now? Ever heard of Shadowrun? Or Universe at War? Or Final Fantasy XI, where you could not only play with PC players, but also PlayStation 2 players? Cross platform is definitely possible, and most likely will be implemented.
Microsoft and Mojang have said that it will be cross platform, so there's that. I'm sure you'll also be able to sign into Minecraft XBLA with your actual Minecraft account too, so you can have your skin/username.
In short, of course it'll have multiplayer. With both existing servers running and the framework of Xbox Live, there's bound to be tons of possibilities for multiplayer. I just hope that for cross platform, you don't need Gold to play on PC hosted servers.