updated about 5 years ago; latest suggestion about 5 years ago
I'll go over
- enumerations, splats
- things you don't realise you can use now - getters, setters
- what's coming up in ES6
Perhaps you can even demonstrate that CoffeeScript is unnecessary!
Coffeescript does make a lot of the arcana around building in missing language features less important. With it being a default in Rails perhaps most Rubyists are now Coffeescripted up?
If so the talk could be refocussed around metapgrogramming - how to do method decoration, mixins, class methods, how similar the prototypical object system is to Ruby's etc.