Mozilla has just rebranded their Weave add-on as Firefox Sync, and I've been using it for the past few weeks. This is exactly what I've been waiting for: the ability to continue my Firefox session from one place to another without losing context.
The Browser Sync Problem
How many times have you left your computer at work running or hibernated because you had dozens of important tabs open and couldn't bear to lose them? Or needed to access a password you'd saved at home while you were traveling? Or wished you could see your work browsing history when you got home?