I agree with Witchy about the game art challenge, it was specific enough but still yet demanding which I think was because of Mikes real world rules.

I think for future challenges, it should be something that not only interests the person to do it because its fun, but will some how provide them with something exciting to learn from (im not saying that the current challenges have nothing you can learn from), like for example, in Mikes game art challenge, people were given an experience of working inside a real game company because of the rules that was brought upon by Mike.

As for the 2 month challenges, never knew about that till now..Its not bad as long as people have the motivation to try and finish the challenge.

As for the Matrix 3 theme for next challenge, what should we do if that is chosen? Our own version of smith? hehehe..Or how about our own version of that big speaking weird looking robot we saw in the trailers.
LOTR3 comes out December, maybe create a new secret monster that Sauron has?

or..oooh! How about create Sauron himself..Im not really sure if he comes back or not the same as how he was before..But eh, just an idea.