I usually don't pre-wash if I buy the fabric from my lqs, or if it is pre-cut...unless there is a noticeable odor, or a bold color, such as red. I do pre-wash if I am not sure where it is from ( like from estate or garage sale, etc...). I also pre-wash flannels, as have been told they do shrink, and it would be a big deal...
I also agree with katier825, I love the quilts after washing-soft and crinkly...gives them the vintage look and feel...