LaunchBar doesn't run jar files, so they need to be turned into applications:
/Developer/Applications/Java Tools/Jar Bundler
- Under 'Build Information', choose the .jar file as the Main Class.
- Select the Java version to use (1.4* uses any 1.4.x version; 1.4+ uses any version that is 1.4 or higher, including 1.5).
- Under 'Properties', tick 'Set Working Directory to Inside Application Package'.
- Press 'Create Application...' and save the double-clickable application bundle to your Applications folder.
This doesn't work for every .jar file, but it does work for WordBiz at least.