According to the report from Eguan, Chinese Weibo active users reached 249 million people as of Q4,2011.
Compared with Q1,2010, its active users grew up 10 times scale, but v.s. Q3 2011, its growth rate decreased 18.0%.
This decreasing maybe caused to "Real-name Weibo Registration", and it will formally start from March 6, so growth rate as of Q2 may be further decrease, or it may be negative growth...
However, on the other hand, zombie user will be not able to do tweet or something actions on Weibo, so will increase the quality of each Weibo.
I think continue to pay attention what impact there are by the number of user increasing and decreasing.
Original article => Eguan