What bugs, if any, have you found in the current batch of native JSON implementations?
FYI - this is meant to be a sort of central repo of native json bugs.
The reason I feel this is important is that the de-facto standard, json2.js, does not install itself if it finds a native implementation, so it is crucial to identify native bugs so that you can decide whether to force json2 to overwrite native if a bug affects your code.