For those of you familiar with the old AppleScript Studio in Xcode, you may find the following information handy to know for Snow Leopard. Apple has changed quite a lot about the way things work, and you have some reading to do to get caught up.
One of the most important pieces of information from the preceding link is the part at the top of the page that reads:
AppleScriptObjC obsoletes AppleScript Studio, which is deprecated as of Mac OS X v10.6. Developers using AppleScript Studio should migrate to AppleScriptObjC, and should start new projects using AppleScriptObjC exclusively. AppleScript Studio development is still supported, but functions for creating new projects have been removed, and the AppleScript Studio palette in Interface Builder has been hidden. To re-enable it, use this command in Terminal, and then re-launch Interface Builder:Hopefully someone else finds this information as helpful as I have. Happy scripting!! :)
defaults write com.apple.InterfaceBuilder3 IBEnableAppleScriptStudioSupport -bool YES
Mac OS X Hints