ZenPundit has a post (scroll down a bit, the blogspot archives don't seem to be working) on Ayn Rand, Objectivism, and the Blogosphere. He speculates on why Rand has had such an impact, but I think it has more to do with the personalities of bloggers than Rand's success.
Among my family, friends, and co-workers, probably only 4 or 5 people have ever heard of her, and I don't think I personally know anyone who read her books. But my experience with the blogosphere is that libertarians are significantly over-represented here, and libertarians usually have had some interaction with Rand's ideas. But that is why I like the blogosphere. Compared to the average citizen, bloggers seem to be more intelligent, more open minded, and less extreme in their political views. You don't see many blogs run by racists, homophobes, communists, luddites, etc. In fact, there are plenty of right-leaning non-relgious bloggers like myself, which is something I don't see in real life. Everyone I know who is a Republican is part of the "Religious Right". (Actually, my old college roomate Jason leaned to the right and non-religious views, so maybe I do know one other person, but we haven't talked about this stuff in awhile so I don't know where he stands right now).
Anyway, the post by ZenPundit is pretty interesting, but I question whether or not Rand has really impacted our culture that much.