Russian Exact Copy of Facebook
vkontakte.ru
vkontakte.ru
one of them was sold for around 5M iirc. The concept works, the entry barrier is low, being copied is inevitable unless you move very fast.
This isn't a bad thing imo though; the local dev teams understand local culture better. faceren and xiaonei both looked like carbon copies of facebook when I saw it on TechCrunch (or something). If you look at faceren now it's completely different.
I also have issues with handing over too much of my info to a Russian company, as their track records aren't that clean.