Hitch is quite a bit different than Sass/LESS. I wrote about this here: http://clint-hill.com/2012/05/06/changing-how-css-works-hitc...
Essentially Hitch looks to add behavior to CSS where Sass/LESS looks to make writing CSS easier. We love Sass/LESS and don't believe it's a competition with the libraries.
Obviously the spec might change and there's no way round that but seems better to hope for the best than to have a custom / branded pseudo-selector. - just a thought.
CSS Selectors 4 (http://www.w3.org/TR/2011/WD-selectors4-20110929/#subject) points out a syntax that is currently using "$". But that has also been suggested as "!" in the past. It's a tough thing to get nailed down, but we decided we'd rather not wait to have the functionality.
Indeed, this is merely one new selector that Hitch provides - there are lots more, and a plugin model which allows an unlimited number in the future. They all follow CSS' forward compatible parsing rules and so, by their nature, they sort of have to follow prefixed pseudo form as a rule.
http://hitchjs.wordpress.com/2012/05/11/content-based-css-ma...