HOW TO: Run Greasemonkey scripts in safari
If you’re a die-hard Safari user, you may want to check out one of Firefox’s best features - Greasemonkey. Using the free software SIMBL and GreaseKit, you can run most of the scripts created for Greasemonkey - in Safari. And Mailplane. And all WebKit apps. So now you can use the genius that is Folders4Gmail while using Safari.
How to run Greasemonkey scripts in Safari - Simplehelp