Well I am starting to believe it is not a joke...*Shivers*

From 4tnz.com:
Well, after months of fans like YOU screaming for a nibble from Rob, your dreams have come true. When the Twilight DVD comes out on Monday (April 6) in England, people might notice a big chunk missing from their DVD case. That's because it comes with the very first autobite!
They took a plaster of Rob's mouth (whoever they are – lucky!) and made a steel copy of his teeth, which they used to "bite" out chunks of every DVD case! It's got his exact teeth marks and everything – which means that if you press it against your neck, it's like Rob bit you (well, without the deadly good looks and British charm, of course)! (Gozde: Rob, if you REALLY did this I hope they paid you well! I mean like 50 years of free Heineken pay!)
4tnz also has some suggested merchandise like pre-used tissues from Rob :) You can read them here.