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Obviously, you have only scratched the surface of AppleScriptObjC development in this chapter. AppleScriptObjC is a new technology, so the amount of documentation dedicated to the subject is currently limited. No doubt more material will become available in time; for now, though, here are some links to get you started:
AppleScriptObjC Release Notes
http://developer.apple.com/mac/library/releasenotes/ScriptingAutomation/RN-AppleScriptObjC/index.html
Apple's AppleScriptObjC mailing list
http://lists.apple.com/mailman/listinfo/applescriptobjc-dev
Five AppleScriptObjC in Xcode tutorials at MacScripter.net
http://macscripter.net/viewforum.php?id=31
The AppleScriptObjC and Xcode forum at MacScripter.net
http://macscripter.net/viewforum.php?id=63
Scripting Events LLC
http://www.scriptingmatters.com/ASObjC
John C. Welch's blog (www.bynkii.com)
http://www.bynkii.com/archives/2009/09/a_look_at_applescriptobjc.html
AppleScriptObjC training videos by Craig Williams
http://allancraig.net