Any practical camera lens is going to give you a perspective projection, which requires the perspective analogue of the Orthographic projection (I'm ignoring a telecentric lens as impractical for this purpose). However, if you have a good telephoto and zoom lens, then backing up and zooming in will probably give a workable approximation to the Orthographic projection. Taking eight or ten images around the globe and one for each pole should give you enough to work with.

Chashio mentioned ReprojectImage ( http://www.ridgenet.net/~jslayton/ReprojectImage.zip ) as an option. It would probably work for this action, but it doesn't have the vertical perspective projections that allow for non-infinite distance perspective projections.

It's possible that Hugin might work for this. I'm not sure if Flex Projector or G.Projector have the inverse Vertical Perspective projection as options.