I've been participating in the OpenStreetMap project for a few months now. I've added quite a few roads and footpaths, mostly around Arlesey. Recently they have revamped the map, so it looks and works a lot more like the Google one. Last night I was at the work Xmas party near Covent Garden. I printed off the OSM map of the area and it was complete enough for me to plot a course back to King's Cross Station. There were a few street missing, but I didn't get to add them due to lack of time and wariness about hanging around dark London streets with a GPS. I did try getting a signal on the train to plot the track, but the carriages don't seem to allow for that. Ironically, I was listening to David Bowie's Earthling album on the PDA and up came the track 'Looking for satellites'. I did manage to plot a bit more of Arlesey when I got back and that has been uploaded. It may be a while before those updates appear on the map.