NOTE: I'm running an unstable system ! I upgraded to mysql version 5.0.19, and eix neatly reports: Installed: 5.0.19 but "eselect mysql list" gives me: Available MySQL versions: (none found) mysql and everything works neatly, but it's not how it's supposed to be. re-emerging eselect-mysql or mysql did not change it.
eselect-mysql is for slotted mysql only (which will be removed soon). You don't need it for 5.0.19.