From MTV:

Consider it official, then: Robert Pattinson and Kristen Stewart are coming to Comic-Con! Summit Entertainment announced today (July 3) that the on-screen Edward and Bella will be at the San Diego show for a "Breaking Dawn" press conference held at the Hilton Bayfront Hotel from 11:00 a.m. to 12:15 p.m. on Thursday (July 12). Start lining up now, "Twilight" fans!

Joining Pattinson and Stewart are plenty of your other favorite "Twilight" stars, including Taylor Lautner, Peter Facinelli, Nikki Reed, Jackson Rathbone, Ashley Greene and Kellan Lutz. Also along for the ride is newcomer Mackenzie Foy, starring in "Breaking Dawn" as young half-vampire Renesmee.