They are actually now called "The Muppet Studio's LLC" (THE is very important i guess) and yeah this took place in late 2006. As for whether they are selling them or have many projects in the works, i have to seriously doubt those customer service people know anything at all, unless they have a set answer written down. Otherwise they'll just say whatever they think you wanna hear, lol. If anything was happening you'd be more likely to hear it right here first so its not really worth calling them.
I also doubt Disney would sell off the Muppets, more likely to just shelve them but they only really own the Muppets in name only anyway - the puppets are built and stored outside Disney, none of the puppeteers actually work for Disney, nor any of the writers, producers etc, the merchandise is designed and produced outside Disney and they very rarely use Disney studios or appear at Disney parks. The only thing Disney about the Muppets is about five people pushing pens at a desk. The only difference now is that even LESS is happening than under JHC, the sad truth is that Disney only really bought the Muppets to sell merchandise and make money from the tape library and DVD sales, anything else is just a bonus.