Russ over at Syntheyes asked on Twitter for this:
how do I call background_image_add on the SpaceView3D of my choice from any #python code–console or textedit? (tags fixed)
If you contact him on twitter please let me know, or you can just answer here and I’ll get it to him.
By they way, there is a new script to export tracking information to Blender 2.57 for Syntheyes users.