Unless you've been watching closely, this announcement was easy to miss. Sun Microsystems is acquiring MySQL. This has ramifications both good and bad.

This will likely affect a huge number of people who are currently using open source web applications; a majority of which are being stored on MySQL databases. Their future viability is now questionable. It all depends on the license and revenue models Sun chooses to adopt.

I would also try to steer clear of the pending 6.0 release as it is likely to involve significant re-structuring of the code to suit Sun's business requirements. It may be a year or three before it stabilises again. Sun is legendary for introducing layers of bureaucracy into development projects.  

While Sun may make public announcements of their intent to continue to provide the product for free [and it should be noted that there was no such announcement in the press release], it is difficult to imagine the corporate bean counters not making a recommendation to derive as much revenue stream as possible from the acquisition.

You can read the announcement here. 

Also of potential interest is this (dated) history of MySQL