Jeffrey Martin of 360cities.net used PTGui to create world's largest spherical panorama:
This image is currently (as of 12/2009) the largest spherical panoramic photo in the world. It is 192,000 pixels wide and 96,000 pixels tall. That’s 18.4 billion pixels, or 18.4 gigapixels! When it’s printed, it will be 16 meters (53 feet) long at regular photographic quality (300dpi). It was shot in early October 2009 from the top of the Zizkov TV Tower in Prague, Czech Republic in collaboration with Prague 3 town hall. A digital SLR camera and a 200mm lens were used. Hundreds of shots were shot over a few hours; these shots were then stitched together on a computer over the following few weeks.
View the panorama at 360cities.net.
Read more about how this panorama was created on the 360 Cities blog.