The conclusion of Neowin's recent trip to Valve's offices was an interview with Erick Johnson who is listed as a Project Manager on the Valve website. Neowin talked to him about Team Fortress 2, creating for the consoles, Steam, and a variety of other Valve related topics.
TF2's "lukewarm" reception on the consoles:
It was the first time they went through the process internally. They do wish they had their own servers instead of using the Live or PSN system. "We will never make that mistake again." We were also assured that "Left 4 Dead will not be plagued by the same issues."
Were they influenced by consoles when doing the Achievements?:
"We knew we had to build achievements for the console. In a multiplayer game we use (Achievements) to try and influence people's behavior online a bit. In a game like TF2, we have things that we want people to do because once they do it they find out it's fun and it benefits the whole team. We also want to reward people that play a lot."
"That's why we started with the Medic because out of all of the classes, the community would say it is the least rewarding, but the most useful, so we wanted to point those guys out as being real useful."
Note: I then asked him if it was safe to say that future releases would include Achievements, such as a new Counter Strike, to which he replied "I don't know what you are talking about."