Sadly it looks like supporting SPDY for Firefox has to be special-cased (the indicator checks for X-Firefox-Spdy: in the headers). Because of this only a couple of the above servers support it.
@Steve, firefox itself injects that header, the server doesn't send it.
Unfortunately firefox doesn't seem to currently set any kind of accessible variable to indicate SPDY so I suggested an idea to detect that injected header for a Firefox port of the chrome indicator extension. Cheng Sun made it an hour later.
Unfortunately firefox doesn't seem to currently set any kind of accessible variable to indicate SPDY so I suggested an idea to detect that injected header for a Firefox port of the chrome indicator extension. Cheng Sun made it an hour later.