MTGSalvation forum user, petalred, reported that the Wizards booth at the Alliance/Diamond trade show, during a seminar, confirmed that one of the most popular Planeswalkers will return in Worldwake. The consensus seems to be that this means that Jace Beleren will be making an appearance in a new form, as Chandra and Ajani already have.

Of course we all know Jace to look like these, and his abilities have begun to really take off as a cheap to cast and potentially powerful card advantage machine. It will be interesting to see what the new Jace looks like. Probably just as emo, and hopefully just as bad ass.