Anything that gets hot and moves in the air can form a con trail.
Propellers which are equipped with electrical anti-icing systems, for example, can form a con trail under the right conditions.
http://project7alpha.com/wp1/wp-content/uploads/2008/11/b-17_flying_fortress.jpg
^Thats a pretty cool picture of propeller contrails.
Contrail shape, length, size etc are determined by many factors. I want to say the reason why a commercial airliner leaves a flat tape-wormy contrail is because of the way a high bypass turbofan engine works.
A turbofan engine is nothing but a big propeller spinning in a tube. It develops almost all of it's thrust by moving air around the core engine, as much as something like 85%.
I remember reading about contrail shapes for an assignment in school, but I have no idea what text book it would be in because contrails can be created by nearly any surface of an aircraft.
I found the bit in the 14CFR FAR about landing lights and navigation lights but I can't link directly to it, and I forgot which part it's under.
If you're super curious about contrails, aircraft, or the FARs (Federal Aviation Regulations) check out FAA.gov.
The FAA writes their own set of text books. They are all Advisory Circular 65.**
For example the general text book is AC65-9A. These are available for free on the FAA's website. You can also look up aircraft by their N number, and EVERY mechanic is listed on that website, with their phone number and address. (I don't have my license yet, you'll have to wait until early next year to prank call me)