Dotdeb.org has released MySQL 5.1.50 packages for Debian GNU/Linux
Yesterday, many announcements have been made on MySQL Sunday. MySQL 5.5 is now RC, and will be GA soon, with many (exciting) improvements.MySQL 5.1.50 for Debian
No, there are no MySQL 5.5 packages on Dotdeb (yet), but MySQL 5.1.50 packages for Debian 5.0 « Lenny » are now available on Dotdeb in amd64/i386 flavours.
This bugfix release embeds the InnoDB plugin 1.0.11.
As usual, please read the Changelog carefully before upgrading.