After looking at devilwoman and ugly_bobs birthday greetings (happy birthday to 'em), i found this site which shows that singing 'happy birthday' is copyright infingement!!! well, arrest me now, i say http://www.unhappybirthday.com/
Dan, pleeeeease don't let them know I sang it,cos I can't go back inside,I can't stand it no longer, i'm begging here dan,Iv'e got to stay out for my sanity.
Of course it's copyrighted... that's why whenever it's someones birthday on a television show or movie they don't sing "Happy Birthday" but instead use "For he's a jolly good fellow" as it's not copyrighted.