Following the update to Firefox stable earlier this week, Mozilla released yesterday updates to its Aurora and Beta versions that introduce some pretty hefty changes for Firefox on PCs.Firefox 11 beta (download for Windows | Mac | Linux) presages some hefty changes for the browser. The biggest one, which wasn't present in the Firefox 11 Aurora release, is add-on sync. You'll now be able to mirror the same add-on installations and settings across multiple desktops. Though Google Chrome has been able to sync add-ons for some time, its implementation has been notably uneven, so it'll be interesting to see how well Firefox handles it. A more silent update process is coming to Firefox on Windows, also mimicking Chrome's updates. Windows' User Account Control will require user input for updates only once; thereafter, updates will occur seamlessly when the browser is restarted. The benefit of this is that security updates generally won't require any unusual user action. This is first available in the new Firefox 12 Aurora (download for Windows, Mac, and Linux). Accompanying it will be a change in the Mozilla add-on policy, so that the majority of add-ons--about 80 percent--will be marked as compatible by default. This is now in Firefox 11 beta.