Temple Fairs, exhibitions and more - events in Beijing during Chinese New Year:
http://www.chinadaily.com.cn/photo/2010-02/12/content_9466117.htm
If unsure where to go, the Temple Fair at Ditan Park (YongHeGong or AnDingMen subway stations on line 2) is a good choice.
China Daily newspaper's Chinese New Year coverage:
http://www.chinadaily.com.cn/china/2010springfestival/index.html