The biggest surprises for me: (copied from my comment on the article):

CSS is also surprisingly low. I would have expected it to dwarf any actual programming language, because IE6 exists, but it's actually lower than most. (Joeboy has a possible explanation: http://news.ycombinator.com/item?id=2899418)

I also find it interesting that functional languages (Haskell, Erlang) are pretty low. These have been thrust into a more mainstream light lately, so I'd imagine they'd be doing worse from programmers who are less experienced in them using them. But they're not like that at all. If anything, Haskell has done pretty good.