Valve have released the latest small update to Team Fortress 2. Following on from the update released at the start of May, it's another that pulls in some community-provided fixes thanks to the source code being available as part of the Source SDK update.
Everything non-commercial
Which means it isn’t truly open source, just that the source code is available.
Don’t get me wrong, I love that the source for TF2 is available, but it’s not open source.