If your ejabberd seems to leak memory it might result out of this bug in erlang’s mnesia database. You can easily find out by starting a remote shell to your running ejabberd and whatch results for the following command:
lists:foldl(fun(Tab, Acc) -> ets:info(Tab, memory) * 8 + Acc end, 0, ets:all()).
The bug is fixed at erlang [...]

Debian (and ubuntu) packages for ejabberd don’t contain drivers for mysql. If you want to connect your ejabberd to mysql you need to get those drivers separately from the external ejabberd modules repository and compile them on your own.
For convenience I’ve built a debian package containing the precompiled modules:
ejabberd-mysql-20090114_1-2_all.deb
Note: this package is not of the [...]