I've just read on James Wallace's blog for the Seattle Post Intelligencia that ANA and JAL will have bidets in the lavs of their 787s.
A Boeing engineer emailed him to say that 22 777-200ERs delivered to Saudi Arabian Airlines were also equipped with bidets.
In the email, the engineer says that he would not use the configuration. My thoughts on this are that I would not wish to know who uses these porcelain extras but I do know they are common place in the Middle East and I do know that one does not discuss one's toilet habits in polite company.
From this, I deduce that this engineer probably does not wash his hands post ablution. If I see him in a bar, I shall be avoiding the peanuts.