This is definitely an interesting move. I'm excited to watch MySQL grow. When I first started using it, it was this little database thing that had basic functionality but didn't have things that we like in MS SQL- like views, triggers, and stored procedures. When my personal development focused on PHP/MySQL, it killed me to not have stored procedures; I had taken them for granted since I dealt with MS SQL professionally. MySQL 5.0 was a big step for it, and it's definitely made it more viable for other projects.
It'll be interesting to see what Sun does with it.