After upgrading to mysql-5.0.18-r30 I followed the instructions at http://www.gentoo.org/doc/en/mysql-upgrade-slotted.xml This failed unfortunately. For "eselect mysql set 1" to work I had to change /var/lib/eselect/mysql/mysql-500.filelist and replace all manpages with the gzipped one, e.g usr/share/man/man1/mysql-500.1.gz instead of usr/share/man/man1/mysql-500.1 Otherwise eselect fails with this error message: !!! Error: File "/usr/share/man/man1/myisampack-500.1" is not suitable for symlink (1) exiting.
fixed in eselect-mysql-1.0.0-r4 to avoid mass recompilation of dev-db/mysql the real fix however stay in mysql.eclass.