Ever since 2000, we've heard news of a new Muppet show being planned, but so far none of these (with the exception of the french Muppet TV) have been made as official series.
In 2000, it was announced that there would be a new Muppet Show from EM.TV, with 26 epsiodes planned. I don't know if it was going to be titled The Muppet Show or have a different title (many articles around the time mentioend that The Muppet Show hadn't had any new episodes for decades, but also acknowledged the existence of Muppets Tonight, while also leaving out The Jim Henson Hour).
In 2002, it was announced that The Jim Henson Company would team up with Fox and Team Todd for a new, edgier Muppet show. This was around the time that Greg the Bunny was being broadcast. I'm not sure whetehr this was to have been the same show announced back in 2000 or an entirely different show. According to Muppet Wiki a pitch tape was made.
In 2005 it was announced that the Muppets would ahve a six-episode reality show parody called America's Next Muppet, which was to have been broadcast in 2006, and hasn't. I've also heard that before this, there was a pilot shot where Kermit, Miss Piggy, and Pepe audition new performers and the home audience would vote (but aside form us, would anybody really care who is and isn't a Muppet performer?).
And then in 2007 there was the annoucnemnt for the Muppet Mockumentary, which would lead to a new series. Could this rumored show be the series that the mockumentary leads to?