One reaction is to take that new content and embrace it. It's not going to work for all situations, but I tend to think this is a healthy way of dealing with the new media - sort of "if you can't beat them, use them for publicity".
EA Sports reaction to a YouTube posting of a "glitch" in the game Tiger Woods PGA TOUR 08 is the perfect example of this. They took a fan made video and turned it into this:
Credit: Aaron