Gnash and BBC glow
One thing I noticed having started to use gnash is that the BBC's iPlayer website (UK-only, I believe) gives a message like "You do not have Flash player installed" - not merely complaining about the version, but actually not recognising gnash as a Flash player at all. Cue some digging. The BBC's pages use glow, an in-house JavaScript library (available under the Apache 2.0 License) to detect whether Flash is installed....