Knowledge sharing in virtual communities makes e-learning more efficient, and inspires learners to keep interest in communities. This paper explores two virtual communities, Chinese Wikipedia and Yahoo! Kimo Knowledge+. Wikipedia is a multilingual, Internet-based electronic encyclopedia, has been created by thousands of ordinary Internet users. And Yahoo! Kimo Knowledge+ is based on Yahoo! Kimo which is one of the most famous portal sites. The paper compares Chinese Wikipedia with Yahoo! Kimo Knowledge+, in order to find out the connections between knowledge sharing and motivating systems in virtual communities.