I recently received an email asking if a person can display a quilt in a quilt show which is from another person's pattern or book. Copyright issues are certainly a hot topic in our community and I always answer, "that is why there are copyright lawyers" - BUT, that said, I called a friend in the publishing world and asked for a general guide line and here is the response.
"My rule of thumb is that the quilt on display should always have attribution for both the book and the quilt designer/author. It is fine for a quilt to be entered just to be shown for the quality of fabric selection and workmanship. For a quilter to enter a contest to try and win money for a design that is original and belongs to someone else would require the permission of the original designer or should not be entered.
That being said we must remember that all the quilt blocks in public domain don't count. And as media people we need to walk a fine line between motivating the quilter to want to show his/her work and making them afraid to show anything for fear of being accused of copyright infringement."