I can't say it much better than this video does, except to note that WB has given its blessing to the fundraiser, and for hardcore fans with money to spare, the rewards are pretty outstanding. I almost played a waiter in a movie with Kristen Bell once, except my scene actually did get cut, so the guarantee here that it will stay in if you pledge enough is one to appreciate.
Oh yeah - Enrico Colantoni does a Gollum impression.. You'll want to see that.
And in less than a day, it's already made the necessary funds. But if you want to help it have a bigger budget, you can still chip in, and there are still cool rewards.