I 'stumbled' across this form of photostitching one day while surfing the internet - it's quite interesting what can be achieved with it. I originally came across this artform on Gadl's flickr account - [link]
There are many ways that you can achieve this effect - Stereographic projections using MathMap plugin for Gimp and polar coordinates effect on Photoshop - this is just a shortcut way in Photoshop i used to achieve the effect - you might be seeing more of these coming up.