I seem to remember Blizzard telling Microsoft that they need an input solution that Blizzard/PC games could work well with instead of just a console controller on their future systems. That could be spinned into Blizzard and Microsoft co-developing the Xbox 720.
The only thing I thought was interesting from short speech, was if those guys are bouncing ideas off of each other. In my opinion that means that Blizzard might make all future games for PC/MAC/XBOX which is cool to me. Don't be surprised if the Blizzard next-gen MMO is for the next-gen xbox, and released around the launch date of the 720.