Wei-Hwa Huang has put up a description of the (Stanford / Bay Area) "Fobik" puzzle hunt in which he participated, so - although I'd love to hear more about it - you don't need to, songmonk :-)
Peter Sarrett has posted issue 28 of the always enjoyable The Game Report board game 'zine, which will include a copy of his report on participating in the Seattle puzzle hunt. Looking forward to it!
Urban Challenge crosses mild puzzle hunt with Tube Challenge-style "visit these locations on foot or by public transport" race. Mainstream, too; 2003 sees events in 23 US cities though alas none of Columbus, Indianapolis and Orlando. Park Challenge in San Francisco is lighter on running and heavier on puzzles. When will this come to the UK, I wonder? You could do a superb one in London at the very least!