I just performed an WordPress auto-upgrade to version 2.9.
Version 2.9 requires MySQL version 4.1.2, and 1&1 was only running version 4.0.27. However, I found out that MySQL 5.0 is also running, so I needed to export the MySQL 4.0 database, create a new MySQL 5.0 database, and import the old data. The details of this, including some editing of the exported SQL commands, can be found on Don Campbell’s blog.
If you notice any errors on this blog, please let me know.
PS: Happy new year.