Hacker news talked about this problem recently http://news.ycombinator.com/item?id=3987660. Unique hardware is always difficult to emulate, and that's why you cut corners. Cutting corers in this field has gotten us quite far http://www.scientificamerican.com/article.cfm?id=graphic-sci....

But the OP of the article is ignoring the philosophical problem at hand: would a perfectly simulated brain bring about sentience? To me the answer is no. A machine can fake it, but its the complex noise of nature that gives us our qualia.