100% agree with all of Chris' points. Additionally I'd like to emphasize that we should continue to strive to be professional and "attack" MySQL by emphasizing the many\most things that PostgreSQL does best.
The funnier than heck anti-MySQL shirts I just ordered from CodePress (MammothDolphinRoasting & FriendsDontLetFriendsUseMySQL) are strictly for wearing around the house. These should continue to be considered as inside jokes for PG community members and never become official PG propaganda. :-)