This is going to be a very interesting poll result. Even 5 or 10% penetration is something remarkable, for a language as widely-used as JavaScript. If you feel like providing any more color beyond your vote, your impressions after using CoffeeScript in anger -- I'd love to hear 'em.
This is a lame reason not to have tried it yet, but I need to first skim a short tutorial that shows how to integrate with jQuery and ideally also shows simple uses of Backbone and Underscore in coffeescript. BTW I love Backbone and Underscore and thanks to them (and also node) JS is actually more fun than ever.
I've played around with the editor at GitHub though and I really like how CoffeeScript reads. That being said, actually using it in the wild seems is road I'm not quite ready to cross yet.