I've long wanted something like Mozilla Sync, so it came as something of a surprise to me that it exists in fairly polished and working form. I haven't seen much news about it, which is surprising, especially from such a well-oiled project as Mozilla; is it in some kind of stealth mode?
Anyway, Mozilla Sync does something very useful in a very good way. It synchronizes your browsing history, bookmarks, tabs, stored passwords (if you have any) and so on across multiple Firefox instances (or other supported apps, I think Seamonkey works too, didn't really look). This is just great if you rely heavily on the awesomebar history like I do - I can be sure all the latest pages I've visited will be stored no matter which system I'm using. Also nice to be able to see what tabs I had open on my desktop when I'm using my laptop.
An equally nice thing about Sync is that it demonstrates how well the Mozilla project has its head screwed on when it comes to openness and privacy. Sync is based on something called Weave, which is a fairly ambitious system for allowing Mozilla products to store data into 'the cloud' (ptooie).
Not with Mozilla. Nope. When you set up Sync, it asks you for an account username and password then for a separate passphrase, which it uses to encrypt all the data before sending it to the server. If you choose to use Mozilla's server, all they get is an encrypted blob of data. They haven't a clue what's in it. They couldn't use it to profile you if they tried. If you still want to run your own server, you can install Weave on your own server. If you really wanted to, you could write your own separate implementation, since they're very careful to document how everything works. The full-fat Weave is a big complex thing, so one Mozilla guy - Toby Elliott - has even created a minimal Weave server implementation which is a tiny little thing you can run on just about any web server which provides enough functionality for a basic Sync setup.
Huge kudos to the Mozilla folks. It's great to have a big body in the rough and tumble online services world that really Gets It.