I don't know besides my company, but as a generalist technical founder, I would be loathe to take someone with experience in x technology over a generalist who'd shown ability to learn new technologies. We work with Flash, clojure, and assembly, which is obviously the weirdest smorgasbord ever. I have yet to see a resume that mentions anything but flash, so I've tried to look for people who look smart and a little arrogant instead, while still being personable.