Yes, flock is built off the same engine as firefox. In fact, a lot of firefox plugins work in flock!
I tried it out when it first came into Beta and wasn't terribly impressed. I'll have to give it a download sometime soon and try it again. Although, I really don't do much "Blogging, sharing, etc."
I'm more of just an IRC guy.
"To iterate is human, to recurse divine." -L. Peter Deutsch