Facebook founder Mark Zuckerberg is facing the music. A legal dispute concerning whether Zuckerberg ripped off Harvard classmates in starting the social-networking site shifted to a federal courtoom Monday. Some of Zuckerberg’s Harvard classmates — who founded ConnectU — want to reopen a settlement they reached with Facebook over their claim that Zuckerberg stole ideas and code from them to start his company. Worst-case scenario is a “a fight for Facebook’s life.” Facebook recently surpassed MySpace as the world’s most popular social-networking site, per comScore.