This kind of idea is hard to evaluate up-front. Sometimes you just have to build it and see but I think you could be onto something.
If you do it, try to integrate visual ways of showing that the app is working, and spend effort on getting that key first answer incredibly fast. Another question to ask yourself is if you want someone to wait and watch the answers come in, or if they'll come back in an hour to see what came in. That decision is crucial to how you build the app.
This article might be of interest: http://www.seo24.org.uk/how-yahoo-or-facebook-could-really-k... Most isn't relevant, but skip down to the text "Think of it this way - today's search engines answer three basic questions:"
It's talking about exactly the problem you're solving, and the value you're providing. Hope that helps and all the best with the idea!
We built something similar, but our focus has been on gathering votes quickly rather than answers. Personally I think something magical that happens when an app crosses over into being truly (and visually) real-time.
- aaron