It has happened before... A couple of weeks after Gabe said on a podcast that the PS3 has to be more open to provide value similar to the Mac platform (that they had recently started supporting) and that "I mean Uncharted 2 is a great game but it can't compare to x PC game [I don't remember which one he named] in terms of value", Gabe announced that Portal 2 and a form of Steam were coming to the PS3.
A couple of weeks!
He was basically teasing "if only the PS3 was more open! If only!" to later appear on stage and praise Sony for opening their platform.
I've found it!
May 19, 2010: http://5by5.tv/conversation/16
The interviewer asks Gabe why they chose to support the Mac over the PS3, because the PS3 is obviously a better game selling platform.
Gabe replied (excuse my less than perfect transcribing skills):
Platform investments like Mac, re-engineering Source to take advantage of OSX and getting Steam running on that, you sort of trying to fire a bullet 5 years into the future and the question what investments are we making that are going to get us closer to where we see ourselves going, we really think that open architecture platforms are going to be the critical determinants of how you create value for developers that, you know...
...World of Warcraft looks a lot more like the killer apps of the future than Uncharted 2 does. Uncharted 2, awesome game, great game, but you know, World of Warcraft has a whole constellation of customer capabilities, so we need to be targeting platforms that do a better job of supporting that kind of application.
If you say "here's an investment we can make", the Mac looks a lot more closer to where we are going to be a couple of years from now, so it makes more sense to make those investments.
It would be super awesome if Sony continues to move in the direction of making the PS3, a more open, you know, look more like a Mac and less than a Gamecube.
Less than a month later, on June 15, 2010 Gabe Newell announces Portal 2 on PS3 and praises Sony for making the PS3 more of an open platform:
"I think Sony will start to benefit from what it's doing. They've done the scary thing and I think it's up to us as developers to make sure Sony and its customers are rewarded. We need to reward Sony for making this decision," he continues. "We need to prove Sony is right."