"I would disagree. The infrastructure -- particularly its scale -- is as much a part of their greatness (perhaps even more so) as the software that powers it. This is implied, though not acknowledged:"
Jeez, I dunno about that. Yahoo certainly has a ton of infrastructure & they don't touch Google.
"So, I really don't think this is a challenge open source can entirely address since there is no such thing as "open source hardware" or "open source bandwidth" that is necessary to match Google's feat."
That's true. I was alluding (or thought I was) to this with the link to a commercial entity to ramp up that part of the equation.