Here are a few links relating to collocation, thanks to Adrian Howard and others. If you know of more, let me know, please.

CSCW 2008 Workshop: Supporting Distributed Team Work

RE challenges in multi-site software development organisations

An empirical study of global software development: distance and speed

Team Knowledge and Coordination in
Geographically Distributed Software Development

Team Knowledge and Coordination in Geographically Distributed Software Development

How Does Radical Collocation Help a Team Succeed?

Working together in “war rooms” doubles teams’ productivity

George Dinwiddie Collocation Page