As per of END OF 2011 these are the LARGEST SOCIAL NETWORKS ON MOBILE
| Name | User | Country |
| Facebook mobile | 425 M | USA |
| Mobile QQ (Tencent) | 200 M | China |
| Sina (Weibo) | 150 M | China |
| RenRen | 61 M | China |
| iMessenger (Apple) | 58 M | USA |
| Mig33 | 55 M | Singapore |
| Twitter mobile | 55 M | USA |
| Blackberry Messenger | 50 M | Canada |
| Mxit | 50 M | South Africa |
| Nimbuzz | 50 M | Netherlands |
| Skype Mobile (Microsoft) | 40 M | USA |
| Gree | 35 M | Japan |
| 30 M | USA | |
| Mobile Cyworld (SK) | 25 M | South Korea |
| Mobage Town (DeNA) | 25 M | Japan |
| Mocospace | 22 M | USA |
| 20 M | USA | |
| FourSquare | 15 M | USA |
| Mixi | 15 M | Japan |
Quellen:
http://www.telekom-presse.at/Die_groessten_sozialen_Netze_nach_mobilen_Nutzern.id.19635.htm
http://communities-dominate.blogs.com/brands/2012/04/largest-mobile-social-networks-today-by-size-of-user-base.html

Thank you ffor sharing this