According to either the same report or a follow on commentary (I'll take a look for it), "silo" or niche social sites did well - BBC Communities was up, as were other more interest-related networks.
Do you think this means that the socnet sector is becoming more easily stratified? There was a great article on the lifespan of socnets on www.modernlifeisrubbish.co.uk which shows the standard rise and fall of networks. Perhaps if a network could secure one of these layers (like LinkedIn has done), it could remain there longer than the average product lifespan. It seems a lot of the inspiration for a new network is just to chase Facebook.