According to ads displayed with my email, Enterprise DB is the real open-source database. At first, I thought that the source for most of their features was not available (I have no interest in Oracle compatability, so I don't want to see that code). But it is available at the download page.
I think that PostgreSQL is amazing for its technology, community, code (nice formatting and documentation) and environment that allows many companies to create value-added versions of it and eventually push back some of those changes to the community. The talk at the MySQL Conference was also amazing, but I had to miss it.
EnterpriseDb has published the source for gridsql that can run queries in parallel on a cluster. Who wants to do a MySQL port?