Dotdeb.org has released MySQL 5.1.49 packages for Debian GNU/Linux 5.0
MySQL 5.1.49 packages for Debian 5.0 « Lenny » are now available on Dotdeb in amd64/i386 flavours.MySQL 5.1.49 for Debian
This is a bug fix release, embedding the InnoDB plugin 1.0.10.
As usual, please read the Changelog carefully before upgrading.