MySQL is an open source database engine and its latest version (5.0) is due for imminent release.

According to an open letter :”open letter(from MySQL’s founders)”:http://www.mysql.com/news-and-events/news/article_925.html from MySQL’s founders David Axmark & Michael “Monty” Widenius – new features in v5.0 include stored procedures, triggers and views.

The lack of stored procedures, triggers and views in MySQL to-date has held it back from being considered on the same level as other RDBMSs such as MS SQL Server and Oracle. Hopefully, this release, when it comes, will enable MySQL to be considered for large db projects and will help drive down price in this area.

A development copy of 5.0 is available for download :”download(MySQL 5.0 download site)”:http://dev.mysql.com/downloads/mysql/5.0.html

UPDATE:
I see the Open Source database market is growing in size and importance