I couldn't pass this info along earlier, since I was at work, but someone I know via email passed along a couple early pre-production drawings of Pixar's upcoming sequel to Monsters Inc, Monsters University. Because of the mutual love and respect between Pixar and Studio Ghibli, and because Totoro's cameo in Toy Story 3 was so well received, the artists are toying with the idea of doing it again.
The idea was proposed back in 2009 during the production of Pete Docter's UP, as well as the US theatrical premier of Ponyo. The Pixar artists pitched the idea to Hayao Miyazaki, and donated this painting of Totoro with his new friends Sully and Mike. The idea of a cameo in the Monsters prequel has been quietly germinating ever since, as both studios are understandably cautious about spilling secrets.
Yes, I know, we all had a good laugh with that April Fools prank. It was a funny joke. But trust me on this one. If you don't believe me, here's a video clip from Japanese television, which features the Totoro-Monsters Inc painting, with autographs by the Pixar staff. Enjoy!