We don't yet know who is responsible for the piece quoted above, but it definitely wasn't actor-comedian Robin Williams (of Mork & Mindy fame). This item's debut appears to have been a 20 March 2003 posting to the USENET newsgroup alt.motorcycles.harley, and from there it was rapidly disseminated via e-mail and blogs, credited to either "author unknown" or no one at all. The Robin Williams attribution wasn't tacked on until several weeks later, apparently because along the way someone appended a genuine Robin Williams quote to the list as an eleventh item:
"The Statue of Liberty is no longer saying 'Give me your poor, your tired, your huddled masses.' She's got a baseball bat and she's yelling, 'You want a piece of me?'" - Robin Williams.
Obviously the Robin Williams attribution for the final item was interpreted as applying to the list as a whole, so now the entire piece is making the rounds as 'the Robin Williams plan.'