I'm sure that Oracle's purchase of Sun is mostly about MySQL - they now own all the pieces of the database (they had previously bought the most commonly used storage engine, InnoDB).
Control is an interesting idea with a GPL'd product though, and I think Matt Mullenweg's comments about MySQL (in the context of how WordPress uses it) illustrate the problem quite well:
Today our servers are running various versions of MySQL, tomorrow they'll be running the same thing, and if need be ten years from now they can run the exact some software. Because of the GPL every WordPress user in the world is protected -- we're not beholden to any one company, only to what works best for us. Today that's MySQL, tomorrow that's MySQL, a year from now we'll see.
Later on he mentions how large the third party maket for MySQL support and add ons is. Combine that fact with the GPL license, and you find that Oracle now "owns".... well, nothing much. Anyone can grab the bits, fork a new version, and stay on the GPL. So if the user community starts getting antsy about Oracle, they can go their own way.
This is why I thought Sun's purchase of the db was dumb, and it's why I think Oracle's purchase is dumb. They could have achieved the same thing by offering stupid amounts of money to the top, say, 10 MySQL core developers. It would be costing them in the low tens of millions to do that...