I've added a new page on the wiki, with information about using enums
in FFI. This is mostly from my own investigations into the source code
several months ago, but I'm not sure it's accurate, complete, or up to
date. I'd love to have an FFI maintainer or expert check to make sure
it's right, and maybe even add some more info. :-)

  http://wiki.github.com/ffi/ffi/enums

- John