It adds this little button to your toolbar, that does the exact same thing as the bookmarklet:
The first time you click it, it will ask to open the myPlex webpage so it can grab your user id (you'll need to login if you haven't already), then you can just use it as normal.
EDIT: Now it will grab your user id in the background when you install it if you're logged in to my.plexapp.com
If you wish to change the account it uses at any point, just login with your new account and visit https://my.plexapp.com/queue/help and it will grab your new user id.
You can download the extension here: http://themacbox.co....ueue.safariextz
Let me know if it gives you any problems and I'll look into it. Or, let me know if it works well for you - that's nice to know too!
Edited by Alex P, 01 November 2011 - 08:53 AM.