Manchester Sport Relief mile and more motion blur opportunites

As I was in Manchester city centre early this morning on some other business.  I took the opportunity to watch participants in the 2010 Sport Relief Manchester mile. As part of a continuing theme I thought that I would experiment some more with motion blurs.  This time I thought I would freeze the background and the stationary spectators and blur the runners and see what I thought of the effect.

Again for the technically minded, all shots were taken on a Nikon D700, with either a 20mm or a 35mm lens.  Shutter speeds varied between 1/25 and 1/6 of a second.  All shots were hand held although I did use barriers and the like for support. Comments welcome.