Interesting read. I enjoyed the photo here: http://www.fhwa.dot.gov/environment/bicycle_pedestrian/publications/separated_bikelane_pdg/page06.cfm
They obviously built MUP-like separated lanes on both sides of the street, yet there is someone going down the sidewalk.
Needless to say, I know opinion is divided on this, but separated bike lanes (15th St Cycletrack for example) were one of the main things that convinced me riding to work was doable a few years ago. The initial comfort level really needed the MUPs/trails and lanes. Obviously, now I routinely take busy roads and while I appreciate the dedicated space, don’t necessarily feel I need it; but, recruiting folks into riding and really bridging that gap to new riders and less experienced ones means it’s a necessity. And, FWIW, I haven’t noticed much in the way of traffic impacts on L or M when those lanes were installed (I worked on M for a few years, including during the installation).