While I sympathize with those who have peanut allergies, I must say that I think that this entire matter has gotten WAY overblown. Peanut allergies didn't suddenly spring up overnight. People have had these allergies for centuries.
I'm in my 40's, and I've had allergies all of my life... and not just one or two allergies - I'm one of those who has lots of food and environmental allergies, with a couple of lesser medicinal allergies thrown in. I scratch test at a "10+" level for many different items, and although I've been through allergy shots a few times (every decade or so, some allergist will insist that the shots have gotten better), I have to discontinue quickly because I have major reactions on just the baby dose chart - and that's with only a fraction of my allergens being treated.
I'm NOT allergic to peanuts, but I am allergic to tree nuts. Those of you with peanut allergies have made my life more miserable, lol. Suddenly I have to make sure that someone isn't trying to feed us soybutter or almond butter under the guise of peanut butter (I'm anaphylactically allergic to both).
If I requested that no one on a plane be allowed to have my major triggers, that would mean that no one would have tree nuts (especially almonds and pecans), carrots, soy, cats (or remnant cat hairs), smoke (or smoke residue on their clothing), strawberries or raw apples. All of these things can cause me to have a major reaction/ full blown asthma attack. It would make my life simpler and less complicated, but quite frankly, I don't feel that I should expect the rest of the world to compensate for my problems. So when I fly/travel (which I do regularly), I explain to the hotels what I need done to my room to make it liveable, and I take extra meds for a couple of days before a flight and bring rescue meds with me. Usually I'm fine. Occassionally, I'll have to use my meds and I'll feel like crud for a couple of days. But that's the way life is. All of us have challenges that we have to face. We do the best we can and move on. But IMHO, it makes no sense to expect the rest of the world to change to accomodate your medical issues.
I'm so glad that my parents taught me to cope in the world around me, and live as normal a life as possible with my allergies instead of expecting everyone around me to accomodate my differences. Also, there are many studies that show that completely isolating yourself from any of your possible allergens may not be a good idea - it increases sensitivity, and can cause bigger reactions when you become exposed.
So personally, I agree with PP who stated that if your allergies are so bad you think that the entire plane shouldn't have peanuts, you shouldn't really be on the flight in the first place. There's just no way to insure that the plane is truly allergen free. The same thing goes for the rides at WDW. How do you REALLY ensure that the child before yours didn't smear peanut butter residue on the ride handle/controls? Do you ban peanut butter from the parks and have everyone sanitize their hands and clothing before being allowed in? I'm truly not trying to be facetious. I just think that this entire issue has lost perspective in this PC age.