It's hard. Natural language processing and semantic analysis is a fairly deep field of knowledge.

One evidence of its complexity is PowerSet itself. PowerSet launched with just being able to search Wikipedia. Wikipedia is a highly, highly structured body of text that is much, much easier for NLP and semantic technology to analyze. Taking the same technology to the garbled soup that is the web is a whole different ballgame.

If you know nothing about it and are looking to launch a product anytime soon, I would focus on targeting a particular demographic with better design, marketing and demographic-specific content.