An Introduction to AppleScript on Mac OS X.
By the way, scripters, it can now do web services (XML, SOAP, etc..), trigger other scripts (perl/shell?), and perform all kinds of Quicktime magic. Plus they've just released AppleScript Studio with the other free developer tools.

AppleScript Studio combines an application framework with a development environment, allowing you to provide sophisticated user interfaces for applications that execute AppleScripts. With the Developer Tools, you'll find an integrated solution for turning your AppleScripts into Mac OS X applications that support the Aqua user interface.

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