At minimum it would kill Google's ability to compete. Every tiny move they made would be under a microscope.

I suspect that won't happen -- with music labels, at least -- for the same reason Netflix didn't look at Blockbuster and think, "We should buy them up!" The whole music distribution model has been based on top-down control and seems very inefficient in light of modern technologies. All signs so far indicate that Apple and Google know that and believe there's a lot more money to be made in coming up with the next distribution model (such as iTunes.)

Sony is perhaps the front runner in this, given its large movie studio and music label, but it's not clear that owning these businesses has been a great boon for Sony's electronics or software.

One can also look at the not-that-long-ago "merger" of AOL with Time Warner as another example of a media/tech marriage where the supposed synergy was vastly exaggerated.

I'm not sure I see any reason for another major tech company to leap in to buying huge legacy businesses given the lessons learned by their competitors.