It's one of those ideas that seem so obvious and that has the potential to change the world, but it is <i>highly</i> dependent of having critical mass. Technologically, it is very simple to implement it. One doesn't need much more than something like CouchDB, and you could have users changing things even from the admin interface.<p>With job4dev (shameless plug), we have something very similar, applied to job listings and company info. We created a "wikipedia for jobs", but lots of the curating needs to be done by hand. We are automating as much as we can, using as many APIs as possible, but there's still the need for human involvement.<p>The problem is, you need to have people <i>wanting</i> to use this. It's the ultimate chicken-and-egg problem. I could see this working if there is some sort of incentive, or even if it ties itself to Mechanical Turk. Without that, it is no different than Freebase, dbpedia, or Aaron's Infogami.