Thanks!
Yes it's Photoshop, I'm cheating hehe..
I take the screenshot with the subject against a clean background such as the ocean or sky and extract it using the pen tool.
After that I go Google Images hunting and merge together some areal photos or horizon shots.
Apply some lens-, motion- or radial blur and voilah!
The final thing left is lighting and fixing up some graphics glitches (bad AA, unwanted reflections or choppy polygons on round surfaces).
If you have some basic understanding of Photoshop techniques you can do these within a hour!
Turning a screenshot like this:
Into this:
-The Spitfire is a screenshot from 71st_dB in IL2: Cliffs of Dover which I used some time ago in a signature for him.