In order to really check what currently has made it into 5.4(there has been rumors...) I wanted to branch the code and see for myself.
Couldn't find it at first in our internal code repository since it's actually not named 5.4 there yet. Fortunately it's also pushed out to launchpad, that means you can easily get a copy of the code using bazaar
$> bzr branch lp:mysql-server/5.4
There is of course also tar balls available from our download page
Anyone curious about what our internal name is? :)