tablecloth math time: $2bn worth, assuming they're worth 10 times their revenue (let's be generous), that would require $200m in sales. they have 10m users, assuming 1% are paying, that means 100k users for $200m sales, meaning each user must spend 2000 dollars per year at Github. Sounds a little high considering the basic plan is $7/month, but with entreprise sales and growth rate, it sounds feasible.
They are probably valued at much more than 10x revenue as a fast growing company. And "users" is the wrong metric as big companies probably make up 90% of revenues, and most of that is not even visible in the public repos.
That is a pretty Anglo-Centric viewpoint I would say. I know of companies in Japan that are moving onto GH:E with users ranging from 20 -> 300+ of which there are probably tens of thousands similarly sized around the world that are not yet on GH or GH:E.
Github recently created a Japanese subsidiary which is telling.
The growth will be in non tech companies starting to do software, and non software uses of git, but noth of those will be slower perhaps. And maybe Windows shops moving to git too.
Sure, I can understand that. But that is based on the notion that Github will stay the way it is, simply a place for collaboration. However, it can amount to so much more, it can spin out its own careers site, like stackoverflow did. The point I'm trying to make is that Github has ludicrous potential, and if you value it based on that 2bn seems rather low.
I don't think Github can get away with job advertising like StackOverflow. I pay Github money; if they start advertising to me I'm leaving. Free sites can advertise at me all they'd like.