No, it's not a joke.  Kraft - the parent company that makes Velveeta, that processed cheese-like product - is reporting that they are having trouble keeping up with demand, and customers can expect shortages on their store shelves.

So far there hasn't been an official press statement from Kraft about the cause, but they have spoken to the media and referenced that this isn't uncommon at this time of the year.  A lot of people use Velveeta as a base for their dips around the holidays.