A fascinating bird's eye view on a hugely relevant topic. This book constitutes the refereed proceedings of the 4th International Conference on Ubiquitous Intelligence and Computing held in Hong Kong, China in 2007, co-located with ATC 2007, the 4th International Conference on Autonomic and Trusted Computing. The 119 revised full papers presented together with 1 keynote paper and 1 invited paper were carefully reviewed and selected from 463 submissions. The papers are organized in topical sections.