Valve Announces Rolling Team Fortress 2 Public Beta

Valve has announced a fresh public beta period for Team Fortress 2, that will run concurrently with the main game.
The aim is to provide a permanent arena for the developers to test out new tweaks and additions. This will let them “change TF2 even more frequently” and, presumably, change it for the better, as they’ll be able to receive feedback and results from potential updates without having to intrude on the main game.
This public beta is, as the name suggests, open to anybody who owns a copy of Team Fortress 2 for the PC. To install, say Valve “launch Steam, open the Library and install “Team Fortress 2 Beta” from your games list.”
Initially, the beta will focus on some Natascha variants, map alterations and rebalancing tweaks. People in the beta are also “automatically granted all the achievement based unlockables.” Other items may be added or removed without warning, depending upon what the beta demands.