Wikipedia isn't the right mechanism. It's fine when you're collaborating on documenting something that's completely objective, but as soon as you get into something controversial it descends into chaos. There's good reason that some of the highest-quality articles on Wikipedia tend to be the ones about math.
Darcs/git might be a better model for this sort of thing: everybody gets their own working copy and can merge changes made to other copies into their own.
I suppose the sincerest form of voting would be merging others' ideas into your working copy. The system could track that and maintain a leaderboard of most-assimilated specs.
Darcs/git might be a better model for this sort of thing: everybody gets their own working copy and can merge changes made to other copies into their own.