Yun Yun is a social search service. Literally it’s Cloud Cloud in Chinese, or it can mean somebody says something if you take the two characters as a verb. Developed by a team of former Googlers, led by the former head of Google China’s Chinese-language search, who went off on their own after Google’s retreat in 2010, Yun Yun received much attention along the way. Before going live to public last night, it had been in beta testing from March 2012.

At the same time, the team has been helping Sina Weibo with mobile searches on Android end and will launch an iOS version later. It is rumored that Sina Weibo will replace its own search engine with Yun Yun’s all together.

Yun Yun indexes entries from Chinese micro-blogging services, offering general search, real-time search, image search and a social network. Its general web search ranks results based on relevance of Weibo messages; the real-time search is based on timeliness. Personalized results are enabled, based on logged-in users’ search data and their interests on other social sites. The social network it has with micro-blogging and Q&A features was aimed to create social content for the search service, but later the team decided not to focus on it.

img:yunyun.com

From the ten-plus Googler team, Yun Yun has more than 200 employees. Apart from the Sina Weibo search deals,  the team is also working for Jike, the search service under People’s Daily, and helping the National Library of China to build a search engine. Liu Jun, the team leader, said that the latter project alone would bring them profits.

Liu Jun told media that Yun Yun was way better than the existing Chinese search services in terms of timeliness. Baidu began indexing Sina Weibo content from March this year and gave a section in the first search result page to show real-time Weibo posts, but later the section disappeared that links from Weibo services — others were added after Sina Weibo — are mixed in other search results. Mr. Liu thinks the conventional search services cannot go any further.

Rumors went that most founding Googlers left Yun Yun after the team had received the rumored 50mn yuan of funding from investors including Zhou Hongyi, CEO of Qihoo, and Sina. Liu Jun acknowledged the investment from Sina and that they dismissed some employees who didn’t perform, saying key members from Goolge stayed. But what has been confirmed is that Chen Liren, one of the Googlers at the team, will join in Pangu Search, a search service jointly built by Xinhua News Agency and China Mobile, as CTO this week.