Urgh, I hope not.
My dislike of her aside, Apple doesn't normally put their products in other peoples video's, shows or commercials. Notice how many Macs have the Apple logo with a sticker over it? Also, in their own ads they typically pick songs that haven't become a hit yet.
As much as I would love Lady Gaga have a part of the next iPhone, I don't think it will happen. Unfortunately, she already has a deal with Virgin.
http://www.virgin.com/media-and-mobile/news/virgin-mobile-stars-in-lady-gaga-telephone-video
Good point, I think this completely rules out the previous post about Lady Gagme being a spokesperson for the iPhone 4G.
(I think that post got whacked or something...can't find it any longer. There was a lot of bickering in it.)