I thought...
that IBM were already shipping a mix of power/x86. Oh wait, wasn't that RoadRunner?
It's no news that IBM was working on Blue Waters and that it would be terrifying, and I wouldn't be surprised if the actual POWER7 project started out just for this system. IBM cannot afford to lose #1 spot on the top500 for PR, Marketing and investor reasons.
These massive projects, typical of IBM, should be seen as such (though they are really cool machines), so that they can inspire everyone aiming at spots between #10 and #200 to give their hardware budget to IBM.