According to this announcement, sourced from Jeremy Zawodny's blog, MySQL AB's new product, MaxDB which is a re-branded and enhanced version of SAP DB, has just been released. It is a GPL'ed product offering both Free Software license, or a commercial license for those who do not wish to be restricted. I think the most attractive point is probably the integration with existing MySQL tools, which is a big plus for developers. And it is a real RDBMS, which includes features like views, server-side cursors, store procedures & triggers, snapshots etc.
With PostgreSQL 7.4 has just been released and Firebird 1.5 getting very close, I think the open source relational database market is getting very interesting. Both of them have less restrictive licenses for commercial close-source application developers, but I think none of them have the popularity and momentum behind MySQL.