http://www.trueknowledge.com is worth looking at! Ask real questions and get exact answers from the service without human intervention (except writing and managing the code of course:))
Another candidate to replace Google from my desktop!
Published
I'm lovin' IT 
True Knowledge are not the only NLP start-up around – another very similar initiative is Freebase, http://www.freebase.com/
The real challenge with the shared database approach is the acquisition of knowledge rather than the technology itself. The expectation from these companies I believe is that “everybody will want to do it” when in reality I believe that anybody who wants to do it, already does on something like wikipedia so why bother doing it on one of these new systems?
If the NLP vendors start looking more closely at intelligence gathering agents they could rapidly define domain ontologies and build extensive knowledge bases with less emphasis on the “good will” of the human user.
An intelligent agent could be as simple as pointing a wordnet based parser at wikipedia – especially as wikipedia already sports a very well defined semantically related data framework.
That being said, True Knowledge is a great example of the type of service that can be delivered using semantic web principles. Tim Berners-Lee would (and no doubt is) proud that his vision of the semantic web has started to really take shape – despite the initial confusion and complexity people are really starting to “get it” now.
SP
NB: The concept i mentioned stems stems from a famous MIT paper by Hugo Liu and the sadly deceased Push Singh:
Click to access BTTJ-ConceptNet.pdf