It's possible that they're building stuff with either a desktop component (RescueTime, DropBox, PikLuk) or a heavy algorithmic component on the back-end (I don't know of any, but then, I wouldn't...) Very few successful startups are only web; most combine a web aspect with some sort of domain-specific processing or data collection, which can be in any language.

There's code written in C and Ocaml in my current startup, but I didn't write it, so I didn't tick it off in the poll. But I could easily see us moving into an area where we'd want to do some back-end processing in a faster language than Python.