Here is a definitive source for the Bethpage green speed, a quote from the Bethpage greenskeeper himself
http://www.nytimes.com/2003/06/15/nyregion/a-year-later-a-new-normal-at-bethpage.html
"Local golfers debate whether the Black Course will be kept in the same condition it was during the Open. So far, little has deteriorated.
Craig Currier, head greenskeeper at Bethpage, said the rough is being kept slightly shorter (2.5 inches instead of 3.5 last June) and the greens are not cut as tight. Last June, they were lightning-fast, a 15 on the stimpmeter, he said."
I don't think we'll ever see greens those speeds again, at least not until the USGA tires of Mike Davis' antics of turning par 4s into par 5s. Even at Oakmont, I suspect we'll be around 13 under Mike Davis instead of David Fay's 14.5 trying to ensure well over par wins. Under Fay, the greens usually ran 1 to 2 feet faster than they advertised whereas Davis keeps the greens as advertised
As for Pebble, I think one of the issues with the greens playing faster in 2010 was the wind direction. In the windswept days of 1992 and 2000 when we had scoring averages over 77, there was an onshore wind. That means the wind was blowing usually against the slopes, so downhill putts were into the wind. I recently watched the 1992 final round on Youtube and downhill putts were coming up short due to the wind. In 2010, the wind was from a different direction, so it is possible that is why the greens effectively played much faster than in previous opens. My green speed estimate could be off as a result