Adding support for generators (yield keyword)

Generators have landed in V8 and Node.JS and they're pretty useful. I think CoffeeScript should have support.

I've hacked in basic support, I'm sure more work is needed but I thought it would be useful to start the discussion.

I'm interested in what the CoffeeScript policy is for features not supported by all JS engines, should they be left out or would it be useful to have a fallback implementation (based on a CPT and a Trampoline?) as a command line option? Neither seem satisfactory but then neither does restricting CoffeeScript user's use of exciting new JavaScript features :)