Lets to several polls to narrow it down. A too open discussion isn't fruitful. Personally, I vote for narrowing it done to a 2D-esque perspective and a game without expensive animations.
To organize it, you'll need a core team (one steady member for each position) that works if no one from the community works on it. An open repisitory like SVN and a task management system like TRAC should be organized so that people get organized.
