I don't know if she "invented it", but I remember seeing Georgia Bonesteel on TV and her books on lap quilting. Here is the part of her site which has all her books for sale http://www.georgiabonesteel.com/store.html I did a small lap quilt a long time ago and was easy to do and the results were good, although I still prefer "regular" quilts. The lap quilting was neat because you could take it anywhere and be able to quilt.
Chris