From the Fluid website: "Turn Your Favorite Web Apps into Real Mac Apps"
Not fully accurate but easier to understand.
When you add the twitter web app it lets you click replies and dm's in the fashion that fits with the trend those apps brought. It's the same for Facebook, techcrunch (tv, other elements) and hackernews.
It's a nice idea although is slightly annoying unless you're on superfast internet as unlike those other apps you have to wait for your internet to catchup.
I think this browser needs speed increases as unless it's the fastest browser or on par it has little point. Interesting idea but not intuitive enough for me.
People still use Rockmelt so there must be a market for this.
With that said I don't think that's at all clear from the copy... just what I'm inferring.
"Raven uses a technique called "site specific browsing" to create a dedicated browser instance for certain websites and their features. It debuts with the most widely used websites including Google+, Facebook, Twitter and Quora. Within each app Raven provides yet another instance for key features. This provides a whole new level of multitasking within a single window. The Smart Bar unifies navigation across many different websites allowing access to features quickly, without effort and with little instruction."
I have no clue what this means. This clearly needs to be dumbed down to be understandable by average users.