You can pick up the app free OTA at http://tinyurl.com/bbsaber in your Storm Web browser. If you like the application, you can donate to the developer using the link on his CrackBerry Forums announcement page.
How it works
Open the app, click the screen to turn the lightsaber on. You can swipe the screen left and right for different colors. When you have a color of your choice, just swing the phone left and right. Based on how hard you swing it, different sounds will play. Click the screen again to turn it off.
P.S. If you’re running .75 OS, you’re not going to hear any sounds. There is a bug in the OS that reroutes some audio channels to your headphone jack. The sound will try to come out the headphone jack rather than the speaker.
Video of the app in action below: