Message from the Program Committee Chairs We would like to warmly welcome you to Beijing for the WWW2008 conference. After a short but influential history of 16 years, the WWW conference is being held in China for the first time, where Internet technology is becoming increasingly critical in almost all fields as China's dynamic economy continues to grow at lightning speed. The advanced WWW infrastructure here connects the nation's 1.3 billion people to the world, and the world can conveniently learn about China via the Web. We are fortunate to be holding the conference in one of the most attractive cities in the world. Beijing is not only famous for its many world heritage sites (e.g., the Forbidden City, the Great Wall, etc.) and rich culture and ancient history, but also presents a modern, high-energy society rapidly advancing on the global stage. The WWW conference series has maintained its excellent reputation as the top venue for presenting the best papers on important problems in the field. It has had a great impact on the research and development of the Internet and Web applications. Indeed, the original paper for the design and implementation of Google's Search Engine was published in WWW7 (1998). To address important emerging areas on WWW, this year we have introduced three new tracks: Social Networks and Web 2.0, Rich Media, and Internet Monetization. We have also organized a new alternate track, WWW in China, which will provide a great forum for participants to learn the latest and most exciting WWW research and development in China. In addition, WWW2008 has invited four keynote speakers and several plenary presentations will be made in the alternate tracks, along with workshops and tutorials. This year, the number of submissions reached a record high: 880 papers were submitted by the deadline. The track chairs and their subcommittees worked hard to select 92 papers to be presented in 13 regular tracks. The PC meeting was held at Yahoo! Headquarters in Sunnyvale, California, during January 8-9, 2008. The three program committee Chairs and Tracks Chairs attended the meeting, which lasted for two days. Each paper went through a thorough evaluation with at least three reviews before the meeting. The committee discussed the top 30% of papers selected for each track. In all, we accepted 103 papers (including 11 alternate track papers), for an acceptance rate of under 12%. We would like to thank all the Track Chairs and all the Program Committee members for their dedication and expert reviews, ensuring a high-quality technical program. Professor Jinpeng Huai and Dr. Robin Chen, the Co-General Chairs of the conference, have provided superb support and guidance to us in preparing a strong technical program. They deserve a lot of credit for the success of WWW2008. We hope you enjoy your attendance at WWW2008 for its excellent technical programs and opportunities for research exchanges with colleagues from all over the world. We hope you will also take time to experience the beauty and wonders of Beijing and other parts of China! Wei-Ying Ma Microsoft Research Asia Andrew Tomkins Yahoo! Search Xiaodong Zhang The Ohio State University iv