One handy feature many Mac applications have these days is the ability to check for updates. There is a free Cocoa module out there called Sparkle which allows Mac developers to easily add this capability to their applications. Fortunately, it is also relatively easy for AppleScript Studio developers to incorporate Sparkle update capabilities to their own applications. This posting provides a tutorial and sample application for adding Sparkle to an AppleScript Studio application.
I first read about this on a MacScripter posting asking about this, and then found this excellent tutorial at Guimkie. There are very few differences between my tutorial below and his, but in my own tutorial I have created somewhat more zoomed in screenshots and a bit more information on the creation of appcasts. You might also want to consult the documentation on the Sparkle homepage and the PDF that comes with the download.