Yup.
Well there was the decision for various site improvements such as the FI purge and the Rep adjustments, but that's the closest things I've seen to being a collectively productive movement. It has worked elsewhere though.
I used to surf a forum that was basically a haven for Spore fanatics, and I was at a time myself. When the creature creator demo came out activity at the site was booming and members started coming out of the wood work to start posting again after years of hiding; a miraculous thing really. Seeing as how malleable the creatures were in the demo I thought it would be cool to make some project out of it. And after dropping by the site a few times I saw a Mew as a creature on one of the members' page.
A spark of inspiration hit me, and with the approval of several members I concocted the CC pokemon contest. It was a big hit, the first 150 pokemon were made with the CC. We even had plans of making a chart of all 150 of them in some form of a collage; possibly a Poke Rap parody. However, for some reason things quickly degenerated even after every creature was cataloged and prepped. I also had a rung of other members handling things when I was away. In the end it was a great concept, but in that case the plan failed; nearly 60 members worked on it.
tl;dr- depends on the community and the circumstance. But it doesn't always work out for the best-- in my case it only works out 50%