Docbert.org has some very cool photos, some of which are in the Gigapixel range, and very high mega pixel counts too. there are 3 in total: Chicago by night, at a Gigapixel (tech info here), Machu Picchu, at a staggering 1.5GP (again, info here) and Sydney by night, at 720MP (tech info here). This is pretty interesting stuff. in the info pages, the photographer says how the photo was generated, but there are no details about if there was a special tripod or anything used to take the photos. Very cool stuff though.