This is a little out of date in some respects, but with recent events it may come back sharply into focus soon. I was curious to see just how much Silk Road was contributing to what was a strong underlying growth trend in Bitcoin price - and the answer seems to support the claims that it was almost entirely responsible (more than I expected, see below).
I doubt there's many people that believe Bitcoin got to the current giddy heights through mass adoption or genuine utility, so the next question is what happens to Bitcoin if the factors driving it up there disappear along with Silk Road?