Seems like the only company REALLY adding to the PEZ production is Disney. Why, just this year they added New Cars 2 Pez (featuring new Sculpts) and added Thor and Captain America to the Marvel line.
Sesame Workshop could take a cue from Muppets Studios here... we could use a Grover and an Oscar to add to their line.
I hope like every other Disney set out there, they add characters to it later on. Late 2009 they introduced new Toy Story Pez with Woody and Rex (A Buzz was already available as part of an overall Pixar line), and when the movie was closer to the release date, they added Hamm, Slinky, and Jesse too.