This is great -- I hate having compiler/runtime advances in Mac OS X always tied to the latest platform release. It can take years before your customer base upgrades, leaving you unable to leverage what I'd consider basic language features -- like fast enumeration, or now, closures.

His javascript example is wrong. Overwrites the button argument being passed in with an internal declaration

Thanks, fixed. I wrote it inline and decided to modify the signature, but forgot to drop the variable.