Just want to pull an important quote out of a blog post:
As I already blogged before, a fork is not enough to keep MySQL alive for all future, if Oracle, as the copyright holder of MySQL, would at any point decide that they should kill MySQL or make parts of MySQL closed source.
When you're working with any open source product, you should in fact do your research and look at who the copyright holder is. Yes, the open source license is important. The copyright holder information is important. Understanding what both of them are to paint the entire picture is doubly important.
I'm not sure how overblown this Oracle / Sun / MySQL really is. It appears at first glance that people heavily invested into MySQL are losing confidence and are beginning to research elsewhere just in case. Me? I'll personally probably wait it out and worry about it later when I see something more concrete.
At work, we use SQL Server primarily, but we do have some MySQL servers still in operation. I pinged my Sysadmins at work about this out of curiosity and was told that they're not concerned about this issue at the moment because the deal is not final and any changes to future development is years away and if MySQL does go the way of the dodo bird, something else will step up and take its place.
To reiterate, software licensing can be confusing. You should definitely do your homework and above all, make sure you look at the big picture. If you don't understand Open Source licensing at all, you should definitely be objective and ask around in the community as everyone is going to have a different opinion of which is better.
Yes, it takes time. Yes, it's worth it. Yes, you should make a small effort to understand. After all, you may have to make your first decision on licensing when you upload your project to riaforge.org.