The last two times I\'ve used MacPorts to install mysql5 +server, the plist isn\'t installed that allows me to have MySQL start on launch. I can\'t remember what, i
The mysql5 +server package variant in MacPorts is obsolete, and is superseded by the mysql5-server package, which you install in addition to mysql5. This allows you to build it after the fact, instead of re-compiling the entire mysql5 package with +server.
I'd suggest to just remove your old mysql5 +server, and install using the following.
sudo port install mysql5-server
That'll build both the required mysql5 and mysql5-server packages for you, and you'll have the mysql5 plist file in /Library/LaunchDaemons. Also note that you no longer need to symlink your mysqld.sock to /tmp/mysql.sock.