Samsung have released an official 6.5 upgrade for the Jack on AT&T. Some of the changes are an updated Internet Explorer Mobile, Windows Marketpalce access, automated free connections to AT&T WiFi hotspots and some other changes under the hood of the OS to make it faster and more stable.
You can get it now from Samsung's site.
Don't forget to backup your contacts, charge battery etc before you go ahead!
[Via Engadget Mobile]