Montessori schools seem ideal. But this looks like a bogus site. There's practically no content here. He even has Larry & Sergey mixed up.
One additional thing in another article is that Montessori let Sergey learn at his own pace, important when he was first learing English:
http://www.momentmag.com/Exclusive/2007/2007-02/200702-BrinF...
There's a 20-minute video here, with a synopsis that credits Montessori with inspiring the 20% time idea:
http://www.ted.com/index.php/talks/view/id/118
Many pages repeat the "friends since childhood" line for whatever reason.