Valve's head states that the Wii U fits into their "scalability model".

For the first time since its official unveiling Valve, developers of titles such as Portal, Left 4 Dead and Team Fortress 2, spoke about the Wii U yesterday. Co-founded and head Gabe Newell gave a keynote speech during New York's Games for Change Festival and was questioned about Nintendo's new console by Joystiq.

Mr. Newell comments that the improved technical capabilities of the console make it fit much better into their scalability model, potentially meaning their popular PC titles could end up on the Wii U as they already do on the Xbox 360 and PS3. Gabe Newell stated that the "love Nintendo" and judging from his comments they may end up releasing titles for the Wii U:

"Wii U seems to be a lot more powerful than the previous generation. It sort of fits better into the scalability in terms of graphics performance and CPU performance, so I think it'll be a lot easier for us to fit it into our scalability model. Now it's a lot easier to look at Wii U and have it fit within that framework."