The December 2009 edition of the Manual for Uniform Traffic Control Devices (MUTCD) has been released by the Federal Highway Administration. Say what? What is the MUTCD? It is the federal standard for signs and pavement markings, so you see the results of it every time you are out on a roadway. More importantly, it specifies how and when many traffic controls can take place, so has an influence much broader than just what you see.
A good introduction to the impacts on bicyclists and pedestrians is on Bike Portland at