http://www.insight-it.ru/masshtabiruemost/arkhitektura-vkontakte/
[ENG] http://translate.google.com/translate?u=http%3A%2F%2Fwww.insight-it.ru%2Fmasshtabiruemost%2Farkhitektura-vkontakte%2F&sl;=ru&tl;=en&hl;=&ie;=UTF-8
some info about internals of vkontakte.ru - russian facebook clone, most popular social network in Russia, #34 in top100 websites according to alexa (btw, Flickr.com is #35).