SinaWeibo is a Twitter-like social network service emerging in China in recent years. People can post weibos (microblogs) and communicate with others on it. Based on a dataset of 650 million weibos from August 2009 to January 2012 crawled from APIs of SinaWeibo, we study the hot ones that have been reposted for at least 1000 times. We find that hot weibos can be roughly classified into eight categories, i.e. Entertainment & Fashion, Hot Social Events, Leisure & Mood, Life & Health, Seeking for Help, Sales Promotion, Fengshui & Fortune and Deleted Weibos. In particular, Leisure & Mood and Hot Social Events account for almost 65% of all the hot weibos. This reflects very well the fundamental dual-structure of the current society of China: On the one hand, economy has made a great progress and quite a part of people are now living a relatively prosperous and fairly easy life. On the other hand, there still exist quite a lot of serious social problems, such as government corruptions and environmental pollutions. It is also shown that users' posting and reposting behaviors are greatly affected by their identity factors (gender, verification status, and regional location). For instance, (1) Two thirds of the hot weibos are created by male users. (2) Although verified users account for only 0.1% in SinaWeibo, 46.5% of the hot weibos are contributed by them. Very interestingly, 39.2% are written by SPA users. A more or less pathetic fact is that only 14.4% of the hot weibos are created by grassroots (individual users that are neither SPA nor verified). (3) Users from different areas of China have distinct posting and reposting behaviors which usually reflect very their local cultures. Homophily is also examined for people's reposting behaviors.