I am conflicted about this. Whilst I see Sun as a big mover in Open Source software, their contributions to Open Office withstanding, I can't work out what the point of "buying" MySQL is. Obviously they've bought the company that produced MySQL, rather than MySQL itself, and therefore the rights to it, but as I understand, it isn't possible to rescind on past licences, ie make it closed source. If they wanted to tightly couple it to Java, that would be a Bad thing, it had a good setup as an independant.
If Sun **** this up, look forward to a new open source db project I suspect.