http://www.snopes.com/photos/animals/cowsnake.asp
Who knows what really happened though. . .ABC also noted that someone posting as the original photographer left a message in their guestbook:
I hope you enjoyed the photo that we took recently while hiking in a gorge in northern Western Australia. The phython was not able to lift the wallaby after trying for approximately one hour. We left him catching his breath on a rock ledge above the pool.