Whatever said:
But Kermit WAS on Sam and Friends, so it's his birthday.
For The Muppet Holding Co. to celebrate somthing they would probally celebrate something they own (they don't have sam & friends). I think the next big Muppet celbration we would see would be the 30th Muppet Show anniversary (2006), The 25 Anniversary of the Muppet Movie (2004), ect. I'm not saying that the 50th of Sam and Friends is not important (because it is), but celebrating it is not likly from a marketing standpoint. It's allready to late for them to do much (like a special production, merchandise, ect) with out it allready being in production and ready for next year. I could be wrong, but it looks unlikely we'll see anything. When the had the 30th celebration it was more a celebration of Jim Henson (and all his work), but with his work now spread over three companies a celebration would be harder to pin-point who/what to celebrate. Also Kermit's did appear on Sam & Friends, but 1955 was not his birthday/creation-day.