Charles Chao, CEO and president of Sina, announced the company’s plans to finally start monetizing its highly popular microblogging service, Sina Weibo, by introducing advertising to the platform within the year.

At the Global Mobile Internet Conference (GMIC) 2011 in Beijing today, Chao stated that they are already planning for the commercialization of their microblogging service. It may be about time as Sina Weibo has already more than 100 million users and is growing at a rapid pace.

Sina has been aggressive early on this year, first by moving to a new domain, Weibo.com, and recently by introducing an English version of its iPhone app, both of which have caused speculation of an IPO spin-off, or even the possibility of going head on against Twitter.

In a totally unrelated note, Jack Dorsey, co-founder of Twitter has cancelled his trip to China.

Chao believes that microblogging will be one of the key factors in the development of mobile Internet and 3G in China. The CEO said that more than 50% of users access the Weibo microblogging platform via mobile, and that approximately 50 million messages are being posted daily.