If you use AppleScripts that you save as applications and are on an Intel Mac, you should like this hint.
In Script Editor, if you save as Application, this will create a PowerPC-only application -- it will launch on an Intel mac, but under Rosetta. However, if you save it as an Application Bundle instead, this will create a Universal binary. The Application Bundle behaves the same in the GUI as an Application -- it is a double-clickable application.
Note that the actual script itself is not compiled in either case, it is interpreted at run-time. What is changed is the wrapper around the script. This means that saving as an Application Bundle on an Intel Mac will not improve the execution time of the actual script, but you should notice a significant improvement in launch time, as Rosetta does not have to be invoked. If you saved any scripts as Applications on a PowerPC Mac and have since upgraded to an Intel Mac, you can always open them in Script Editor and re-save them as Application Bundles.
Mac OS X Hints
http://hints.macworld.com/article.php?story=2006080109510225