No. Long files names were incorporated into unix systems long before the days FAT, or even DOS.
But not long AND short file names on one volume - i.e. DOS-compatible ones AND Windows/ROS/whatever-compatible ones.
If is true, it would effect many things, but I can't see Microsoft enforcing it, it would alienate themselves.
I think they are - especially when it comes to vendors formatting their flash cards, smart cards, digital cameras with FAT!
Just my 2 cents ;)
Oliver