Realistically, Apple hasn't even been all that innovative at all. They haven't really come up with all that much that's new, they've just been making existing things looks nicer than everyone else does.
If you look at OSX and Windows 7 from a purely technical angle, they aren't actually all that different. They both have an increasingly analogous set of libraries (Cocoa looks more like .NET every time I visit ADC's site, though Apple still isn't in Microsoft's league as far as development tools and languages).
Apple has done some innovative things, like OpenCL -- which, naturally, Microsoft is copying... but in the end, the differences between OSX and Windows 7 are largely user experience, not technology.
That's not a bad thing, but it does highlight the fact that most of the "innovation" that Apple has been touting over the years hasn't been innovation, it's been lambasting Microsoft for not having its act together.
I suspect that Apple is focusing on mobile computing and the cloud partly because there's no technical way to differentiate its computers from everyone else's any more. Their internals are built by the same companies that build everyone else's internals... so the only differences left are the operating system and the chassis. That's not going to do wonders for their margins.