Hearing from THR.com, that the co-creator of Flight of the Conchords James Bobin has been recently signed as the director of the film definitely bolsters my optimism. Bobin wrote and directed several episodes of Flight of the Conchords and also worked in a similar capacity on The Ali G Show. Admittedly I would have preferred Mr. Dante to direct Kermit's first theatrical outing in over a decade, but this should still be pretty great.
I should mention that Jim Henson Studios have been rather active these days on YouTube with their Muppet Studio Channel. They do a pretty outstanding Bohemian Rhapsody.