Browsers were once our gateways to portals.
Browsers then became our windows to the web.
Browsers are now the biggest possible windows through which we access our digital lives.
As we have transitioned from a web of access to a web of content and connections, it is only natural for the browser to adapt as well. And with Facebook Connect enabled on virtually every site we visit anyway, wouldn't it be natural for a browser to feature Facebook at its core? Not really.
To be fair, RockMelt is a phenomenal concept with some very strong supporting characters. However, I'm not sure that Facebook warrants a browser of its own. I love to connect with friends as much as the next guy. And between my Hootlet, Bit.ly, Share This, Del.cio.us and dozen or so other browser add-ons, my browser is already a social portal. I'm just not sure that Facebook is strong enough on it's own to warrant a change in our surfing window - the browser.
Sure, I'd love to bring my social life with me across most of what I do. And it would be great for my browser to integrate all of my social IDs into it's very fabric and design. I just don't know that (A) Facebook is the social network that I care most about, and (B) that this warrants it's own browser.
Facebook chat can probably stand it's own on as a desktop application similar to AIM. As could a future Facebook email solution. As could an "upload to Facebook" micro-program. But I just don't know that I care to do my banking, view my video, blog, tweet, chat, research or order lunch in a Facebook environment. Facebook is good for a lot, but it's not yet my everything, nor should it be.
That being said, a browser with embedded social push and pull functionality, a FriendFeed-esque browser add-on, could be VERY interesting.