They're using the WebKit rendering engine. While Chrome is a great browser, I'd hardly say it was "made from scratch".
One of them, apparently, used to be used by the CEO, and had Flock installed on it. This was my first introduction to the browser.
Does RockMelt have a business model? dunno. But RockMelt solves the pain of twitter/facebook/linkedin fire hoses (for me)
A dedicated browser for social networking like Flock always seemed superfluous to me. The recommendations of the Flock project point at this: use other free browsers (preferably FF) with the appropriate extensions.
Edit: Nevermind. I didn't realize that Flock 3.0 moved to webkit.
"Wanted to destroy something beautiful" - http://factoryjoe.com/blog/2005/12/29/wanted-to-destroy-some...