The language syntax is pretty much stable at this point -- getting to 1.0 is now mainly a matter of shaking out the edge cases in parsing, and solidifying the compiler as much as possible.
Fortunately, you don't have to take my word for it. Even if the CoffeeScript compiler were to disappear in a puff of smoke this afternoon -- you'd still be left with pretty-printed, quite-readable JavaScript. It's not like depending on a beta of a VM or interpreter.
Any idea how far away you are from putting out something one might consider 'stable'? I'm in the government, and it's effectively impossible to use 'beta' code here.