Forgot to say this earlier, but even though Musker and Clements are solely responsible for the story, the screenplay will be written by the same man who just won an Oscar for the screenplay of 'Little Miss Sunshine'. I didn't get a chance to see that movie, but supposedly it was pretty good, (heck, the guy just won an award for it), so this looks good for the level of care going into 'Frog Princess'.
(Oh, and this is totally off topic, but Toy Story 3 is finally in production! Originally, it was only put forward as another typical Disney sequal with no regards to the quality (the story was completely lame and rehashed from TS2), as Pixar was no longer involved. But then when Disney bought Pixar back, they were apparently horrified with what was going on and so Lasseter and crew took over the project and put together what he's now announced is "a great story". Both Tim Allen and Tom Hanks are onboard for this, and everything is looking great. This is one sequel I actually *want* to see.)