Yododo, mipang, tuniu and cn0km.com are some of the leaders in Travel 2.0 services in China according to the China Web2.0 Review blog. Yododo is a travel planner and info site. Mipang is a social network. Tuniu is a travel portal with Digg style voting features. Cn0km is a destination wiki/info site.
This is one of those nice web moments where I have not been able to look into sites like these because of my language inadequacies so can simply point you all to someone who has done all the hard work.
Originally found the link on the China Industry Travel Blog.
UPDATE - Claude at Les Explorers blog has an interview with Yododo CEO Marriane Miao here