It's neither prior art (though it was started prior to the recent patent publicity), nor a re-implementation (as stated in the readme, it's just a wrapper around OS X's NSLinguisticTagger).

Why can't it just be a useful tool? I'm looking forward to using it while writing project documentation and will be working on editor plugins using the JSON formatted output (https://github.com/stephencelis/syn/commit/d2d36473f7295c6cf...).