thought github was for open source stuff. this sounds a little pointless. aside keeping proprietary software ahead of the open source stuff so people buy it

It's an interesting move that's for sure.

Supposedly GitHub is worth 5 billion dollars. So, it looks like Microsoft could buy valve pretty easily.

Except Valve are private and no, they won't. 

This has nothing to do with Valve either. 

Valve is worth about 5 billion and Gabe owns the majority of the company. Maybe Gabe wants to sell since he is getting up there in age.

GitHub are also private.
And you are correct, it has nothing to do with Valve.

Basically... These purchases can't go through unless the shareholders (Aka. Gabe for Valve/Chris for GitHub) give the go ahead.

I don't know how I feel about this. I guess I could always swap to another Repository if I don't like it.

Well, if anyone needs it, it's Microsoft. Must be a nice change for their developers to look at good code for once.

Getting on with age doesn't automtically say that he's going to sell  the entire company to MS.

He doesn't agree with MS at all, so I doubt he'd even sell to them at all. 

He loves money.