Google signs on as MySQL contributor

The search giant is spreading it's wings far and wide.MySQL AB announced a few days back that the leading open source database will include code contributed by Google inc., along with some security improvements in the development roadmap through 2009.
That's great news. Hopefully MySQL users world over would get to derive the benefits of several customizations Google has been doing on the db engine.Albeit, the extent and areas of contribution from Google would be interesting because if this move is more strategic than philanthropic, then Google obviously would be choosy about releasing contributions to the MySQL code base rather than opening the flood gates.
Also, why is it that the company has chosen to begin contributing to MySQL only and not any other platform that the company uses and customizes to a great degree for better than optimal performance, like Linux or Apache, etc.Why did the company chose to partner with IBM to train university students on cloud computing ?
MySQL had also announced earlier this year that the enterprise source code would not be available for non-clients.So one is forced to question whether contributions made by Google would also be split amongst the two versions ?

Also, interestingly is there a paradigm-shift in the open source world where in contributions from individuals begin getting overshadowed by those from the big guns ?