Per Bug #194561: Opening a new ticket for a version bump to 5.4 branch of MySQL. I don't see a similar bug, so creating this one.
For those interested, the mysql.eclass now basically supports 5.4/5.5 and I've created some ebuilds that work for me: http://svn.hboeck.de/overlay/dev-db/mysql/ Nothing special in there, 5.4 is just a copy-over from 5.1 and 5.5 needs a minor adjustment for the filename.
5.4/5.5 are coming, as soon as they finish passing my runs of the testsuite. Based on hanno's overlay changes.
5.4 in the tree. 5.5 coming overnight.
5.5 in the tree now too. I had to turn off more tests that were failing due to USE=-latin1, I'll consult upstream next week on them.