This article is from the of the muppets FAQ, by Craig Silverstein with numerous contributions by others.
You would have to attribute a great deal of stupidity to PBS to have them canceling one of their most popular programs. While PBS funding is always in danger, "Sesame Street" would be among the last shows to go -- in fact, PBS has renewed its contract for "Sesame Street" through 2002. If you see a petition claiming otherwise, ignore it. (This is a good rule of thumb for email petitions in general. Since there is no way to control forgery or repetition of signatures in email petitions, these petitions are universally ignored.)