This started out as a reddit reply to
Alex Iskold's article about semantic search engine technology. Alex suggests that the reason why we haven't seen the semantic web as overtaking as the search technology of today is because of two points: that they won't provide better search results today and that the current semantic search engines have UI problems. At the same time, he claims that (wrt. to the search results) "emantic search is going to be big and it is going to help us answer questions that we simply cannot answer today - complex, inferencing queries asked over the entire web as if it was a database." I think that the UI point is irrelevant, or perhaps only relevant at this point in time.
I agree with the search result point, but I'm much more sceptical about the future results to expect.
