Windows/Mac/Linux: Firefox 4 is out with another beta, and this one has mostly bug fixes — more than 1000 of them, actually. But Mozilla has simplified and improved the process for setting up syncing between desktop and mobile browsers.
Mozilla's servers offer up downloads of Firefox 4 beta 8 (for Windows and Mac, and other languages/OS on the FTP server), but their home page for the beta, and "Check for updates" hasn't quite caught up (we'll update the post when it does). In the meantime, grab the more stable version of Firefox 4 and tell us what you think in the comments.
Mozilla Firefox 4 Beta 8 Fixes [Mozilla]