KStew back in LA?

Supposedly Kristen arrived back in LA on Monday, after a whirlwind weekend @ the Sundance Film Festival in Park City, Utah. What I want to know is...who's the dude? It's not her bro, I know that much. Anyone else have any ideas?

(and no Mrs. P, I'm about 99.9% sure it's not her new beau, and if it is, I will eat dirt.)

Update: Twicrackaddict pointed out to Mrs. P that KStew is wearing Rob's shirt...supposedly the one from the New Moon poster (I doubt the poster part)...AND, you can tell it's a man-shirt because of the buttons...If you look down at your buttons ladies, they're normally to your left. If men look down, they are to their right. (SQUEEEE! They're sharing clothes!)

You can scope out the rest of the pics at Kris-Stewart.org