Valve on DirectX 10

During an interview on Left 4 Dead (actually, this is part 2), Valve's Doug Lombardi talks about the source engine and Direct X10.

PCGH: Is DX10 the way to go and therefore the way of future graphics.

Doug Lombardi: Well I mean there is always that tradeoff between taking the time to adopt the engine to a new API, right. And for us we feel like there still things in DX9 that we can achieve without having to go through the pains of moving to DX 10. (...) So for us as a company and our game designs, we've looked at the tradeoff of the work to move to DX 10 and we have always kind of felt that there is not really enough there for us to delay whatever game we are working on by six to eight month just to say we've a DX10 game. (...)