I would be very surprised if GitHub wasn't rapidly approaching being cash flow positive. Since they've been out of beta for only a few weeks I think that's pretty good. Personally I love their product and it seems I'm not the only one.

I think they're a great example of the types of companies in DHH's talk: have a product your users love and charge a price for it. As a bonus they also offer a free version for open source work for which they have my respect.