I just found out about this wonderfull techneque from the people at bldgblog, I have yet to find out a way to replecate these results, but at a guess it is similar to stereo photography. From the photos I have seen it would apear to me that you need a helicopter and some newfangled piece of cool camera lenseness but the below photo has been taken from ground level so I am thinking maybe it could be possible for me to have a go. The photos are manificent works of art, and I am going to search google for a method of reproducing them with my Canon 350D 
Im sure there is a method that can be used without having to use any fancy optical devices. The first thought that poped into my mind was taking several photos which are ofset by one another by a degree in one direction then in photoshop layering them and using darken or hard light or such like to get them to mix to produce a final photo. I also guess that full manual use of the cameras focus is mandadory so as to keep each photo focused on the same point and thus give a good depth of field and a fantastic end result. I shall post my finding here when I get round to experimenting.
Edit: Just found this fantastic gallery of photos using similar techneques to the above they are awsome 
