Create a 3D Picture from one image

After the latest edition of .net magazine landed on my desk with a free pair of 3D glasses I was inspired to create my own 3D picture.
I used photoshop for this but assume you can do the same with most photo editing software.
Problem
For the best results you need to take a picture of the same subject from two angles that are a few inches apart – I didn’t have the time (or be bothered) to do this, so just used one image.