Only to the extent that Firefox is a JavaScript library. I think the major idea is that there is some application whose operation is very broadly directed by the embedded language, in a sandbox-like environment designed for the embedded language. For instance, you could write a video game whose graphics and collision detection and whatnot are all C++, but have Haskell bindings so that all the high-level game code would be Haskell. This isn't all that different from the usage of the much more C-like UnrealScript, which is used for exactly this purpose and is both statically typed and compiled, if I recall correctly.
