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.
