I'd be curious to learn more about them too but Jason Knight I'm afraid ppl are going to be scared to reply lmao.
I suppose my new ECMAScript 6 book that's coming today will explain more. I assume these are similar to C#'s lambda expressions.
I don't think many of these syntactic additions do anything that other older methods couldn't do but they're adding shorthand to the language but this is just my speculation. Will be interesting to see a JS pro get on here and tell us.