Browser synchronization has been available to Firefox users for more than a year from Mozilla's Weave add-on. The latest version, still in beta, promises to emphasize its ties to the browser with a new name and better features.
When the final version is released, Firefox Sync 1.3 will include Firefox Mobile (Fennec) support, the ability to synchronize more Firefox preferences, bookmark backup that initiates before the first sync to prevent data loss, and major interface and performance improvements. Account creation should be easier, with a revamped "wizard," and the changelog for the beta indicates that many of the pre-existing features will simply work better.
Along with announcing those changes on his blog, Firefox developer Tony Chung said in the comments that Mozilla plans on integrating Firefox Sync 2.0 with Firefox 4. Firefox 4 is expected to be a major update to the current Firefox trunk and is currently expected around November of this year.
The renaming plan has caused some debate in the developer community because the add-on has been at least partially functional with two other Mozilla programs, e-mail client Thunderbird and Netscape Communicator heir SeaMonkey.
Firefox Sync 1.3 beta 5 is currently available from the Mozilla Weave Web site. Click on the green bar for the experimental version. The full changelog can be read here, and the stable version of Mozilla Weave is here for users who want to regress from Firefox Sync or try out a less risky version.