One notable but unsurprising detail about the Christmas flight bomber is that he spent a lot of time in the bathroom.
"In an affidavit filed in court, an F.B.I. agent said that Mr. Abdulmutallab stayed in the bathroom for 20 minutes before the attempt, returned to his seat, told his seatmates that his stomach was upset and covered himself with a blanket. It was then that the smoke and popping sounds began."
So, how long are we going to allow people to stay in airplane bathrooms for long periods of time? This already was a fire risk (that's why they have special smoke detectors in there, so secret smokers don't cause an in-flight fire). This situation is more serious.
I don't have any solution for the privy problem that doesn't raise privacy issues -- and possibly make being a flight attendant even less fun.