I think the question for Powerset now is how quickly they can make their technology apply to other websites. My guess it they choose wikipedia because the html is fairly tame...it's much easier to semantically parse wikipedia than it is the wild wild west that is html formatting on the web.

If this is the case, then they might be in trouble. They built up too much hype to just be a search tool for wikipedia. If they can upgrade their technology and search much more of the web then we'll have a better idea. For right now? Meh.