- My selection is already made - around the frog and the gimphelp.org text. So I invert what is selected to get the "background"
- Choose Edit>Copy for your selection
- Next I applied a "Motion Blur" to the background.
- Since the blur is a bit too overpowering, I "Paste Into" the background I just blurred.
- Then I selected the Layers dialog and knocked down the opacity of the pasted in layer (the original appearence)
until enough of the blurring showed so that I thought things looked good.
- Choose Layer>Flatten Image
- Finished. I unselected things to get a better look.