The following lists hosted at Apples Developer site are useful for Carbon developers:
A full list of Apple's public mailing lists can be found [here].
You can search through the mailing list archives [here].
Please note that the mailing lists are no official support channel and not a replacement for formal support or bug reporting procedures.
However, though there's no guarantee that every posting will be read by someone at Apple several Apple engineers are usually around and may to contribute to the lists.
(Hint: if the Apple Lists Search is too slow, in particular when searching for multiple word, try a Google search: "kCoreEventClass site:lists.apple.com")