"The mod tools have to stay on the PC side just because there's a bunch of depedencies that require the Windows platform," he said. "But the content that comes out is agnostic, and so we will be seeing that on all the platforms. Depending on the platform you're on I should say, will depend on how we're delivering it."
The PS3 version will probably deliver the content via its own recently revealed Steam partnership. It's unclear right now how Valve will deliver content to the generally more closed Xbox 360 platform.