I've never been particularly bullish on Twitter's ability to make money, mostly because their business model isn't obvious to me. That being said, the fact that they are going to exceed $1 billion in revenue is really impressive to me. I've heard various bearish news over the years: Rails doesn't scale, they will never make money, user growth is slowing, etc. For a company with so many people betting against them, they seem to be pretty good at overcoming challenge's! It won't surprise me to see them making the big bucks in a year or two. Good luck Twitter!