The Mozilla Labs team has been working very hard to move the core part of Firefox Sync (nee Weave Sync) into the main Mozilla source repository. They finished a few days ago. Now any Mozilla application can start to use the core features of Firefox Sync without requiring the user to install an add-on. The system is built right into the application.
The Mobile team integrated the basic user interface for Firefox Sync directly into Fennec. Now you can synchronize your tabs, history, bookmarks, form data and passwords – desktop to mobile device and back again – without installing an add-on!
If you’re using a nightly Fennec 2.0a1pre build, take a look in the preferences area for the Sync settings. We’re not finished yet. Plans for Fennec 2.0 include re-organizing the UI for accessing remote-synced tabs.