I guess I don't understand the anger/annoyance. Outside of Cast Members, the only people that would be interested in this project at hardcore Disney fans. (The general public doesn't care about the Joe Rohde or other behind-the-scenes folks.)
Announcing it at a Disney fan convention makes perfect sense to me.
Plus, I don't get why anyone would fault Disney for the way bloggers reacted. Even if Disney disliked the way the announcement was being reported, they couldn't step in to stop the hype. Doing that would have been a huge slap in the face for the series/book creators and all the Cast Members who here interviewed.