WordPress currently requires MySQL 3.23.23 or greater. We’ve long avoid bumping our requirements so that we could accommodate the widest variety of hosting environments. We understand that people don’t want to upgrade a platform that is working just fine for them. However, supporting these older versions adds development and support costs. Recently, a commit went into trunk that bumped the MySQL requirement from 3.23.23 to 4.0 or greater. Considering that MySQL AB is dropping support for 3.23 and no longer provides binary downloads for 3.23, is it time for WordPress to move on? How many of you are still running 3.23?
Please note that this requirement change affects the upcoming 2.1 release only. The WordPress 2.0 series still supports 3.23 and will for the foreseeable future.