Apple has given AppleScript Editor in Lion the ability to access Cocoa frameworks. In a nutshell, this means that AppleScript Editor can be used to create quite complex programs (which can run on Snow Leopoard and Lion only). But as far as I'm concerned, the big bonus is the ability to create single-window UIs for some of my AppleScripts. Instead of using two or three display dialogs or choose from list boxes, a single pane incorporating many options settings can be used. I've already created some of these kinds of interfaces in the form of helper apps that I bundle with a script. But now, I can make these UIs a part of the script bundle itself, without the need to launch additional helper apps. Plus: wicked fast.
Look for these sorts of scripts and updates to scripts coming soon.