The title is slightly misleading - In fact the compilers have been available before as part of the .NET Framework (or Windows SDK) and are most likely sitting on your windows machine (try c:\Windows\Microsoft.NET\Framework\v2.0.50727\csc.exe).

Indeed, and have been free for a long, long time. The only thing they charge money for is the IDE.

and even then, there are free editions of that too (express)

Odd title, they've always been freely available, just bundled with the larger .Net framework

Wow, a programming language compiler I don't have to pay for... Somehow not that exciting a development in 2013.

They have been part of the .NET framework since .NET 2, anyway. The only change now is that you can download them separately in a package with MSBuild (which was previously only bundled with Visual Studio or the Platform SDK, if I remember correctly).

But indeed, that's not a very big change, given that they were free before already.

You never had to pay for. The news is that you can get it standalone from the .net framework.

As for free as in freedom, AFAIK it hasn't been made open source.

I'd rather pay for my entire, well-integrated operating environment and technology stack than use HTML-fail/CSS/JS or some other Frankenstein's monster cobbled together from open sores and so-called standards because...it all just works.

This is different and somewhat confusing to me. The Command Line Tools are just broken out from a large IDE that isn't necessary to run the results.

In this "Microsoft Build Tools" case, they're separating the tools from their runtime support (the .NET framework). You need the framework to run whatever you're building, so it doesn't seem like much is gained by splitting them up.