extra @ character
does not compile
this is the new dictionary syntax and not a bug--please update your compiler!
I just ran into this as well. It seems the new array & dictionary literals syntax requires Xcode 4.4 or newer, but Xcode 4.4 and newer no longer support the Mac OS X 10.6 SDK.
The development requirements listed on the ARC page should probably be updated to reflect this (I know, it's not ARC-specific, but it's the the only place requirements are listed). It could also be added to the ProblemSolution page.
@morgant thanks for the suggestion, i've updated the ARC section, the ProblemSolution section and the readme