Recently the Leopard Movies widget, which Steve demoed along with Leopard, stopped working in Tiger. Leopard's built-in Movies widget continues to function, while in Tiger, it gives an error of "invalid zip code." You can make this widget function once again in 10.4.
Navigate to /Library/Widgets and find the Movies widget. Control-click on the widget and choose Show Package Contents from the pop-up menu. Then open parser.js in your favorite text editor, and replace all occurrences of A99D3D1A-774C-4914-9E3B-18645117428A with DE7E251E-7758-40A4-98E0-87557E9F31F0 and save. Close any open movie widget in Dashboard, then re-open it. Now it works.
[robg adds: I can't test this one here...]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20080609093907318