Apple runs mailing lists for a variety of programming topics, including Carbon, Cocoa, AppleScript, and other technologies. Apple engineers frequently contribute to these lists, so they are a good place to get detailed answers to your questions. You can find mailing list archives online at http://lists.apple.com/archives/.
The Omni Group sponsors a few mailing lists for Mac OS X, including development lists for Cocoa and WebObjects, and a mailing list for Mac OS X administration. Archives are also available online.