When Power View appeared, one of the big outcries was "but what about connecting to existing cubes!".
Great to see that the SQL Server team have addressed that. A CTP that allows connecting Power View to SSAS Multidimensional cubes is now available:
http://blogs.msdn.com/b/analysisservices/archive/2012/11/29/power-view-for-multidimensional-models-preview.aspx
Help the team get this out the door by trying it and providing feedback.