*phew... it is fixed now

... resolution:
I'm running Resin, and probably just like any other Servlet/JSP server, you need to have the MySql driver located in the /lib directory.
I don't know exactly which /lib directory was needed, but I put it in every /lib directory I had in my $JAVA_HOME install dir, and in every /lib directory in my Servlet/JSP server installation.
(including WEB-INF/lib/)