This is more of a reminder to myself than anything. To install the mysql gem on OS X Leopard and use a macports MySQL install.
First remove any previously installed mysql gem
$ gem uninstall mysql
Then install, giving the correct Leopard archflag and macports mysql_config directory
$ env ARCHFLAGS="-arch i386" gem install mysql -- --with-mysql-config=/opt/local/lib/mysql5/bin/mysql_config