Are there any open source Lisp compilers suitable for real-time embedded applications? I.e. with incremental garbage collection, customisable memory handling, small footprint, etc.
Edit:
To clarify, by "compiler" I meant native code, not bytecode interpreter (though the suggested interpreting implementations for microcontrollers are interesting for being a lot smaller than what I thought possible!).
Take a look at Picobit and the code, which is a Scheme for microcontrollers. There is also tinyscheme, but I don't know how suitable it is for embedding into smaller processors.