Reminds me of my own (open source) project which does the same based on Chrome: https://github.com/albertz/ChromeWebApps

It uses (by purpose) the same session though as the main Chrome instance.

But it should be possible to implement an option to use a separate session. This might even be much simpler than my current approach (which not only shares the session, it also uses the same Chrome process).

I like the idea, but I'm not sure if I can trust this level of sand-boxing. Does it also use a separate cache (web history, etags, image cache, web cache, etc)? a separate Flash storage? Silverlight storage? HTML5 storage? If any of them are shared, something along the lines of Evercookie would have no problem maintaining cookies across the apps.

Cache is completely separate, Flash and Silverlight (and plugins in general) aren't sandboxed, which is why I deactivated them for my Facebook Browser. (no more embedded youtube videos, but they open in my main browser, works just as well)

Doesn't fluid share the same default cookie store as Safari?

It definitely does on my version, which is 6 months old, but it caused me to not use it.

Not any more. He rewrote it and made separate cookie store a paid feature.

Great - going to get the new version. That is much better