Burkett is still the most likely source. I offer two reasons:
1. An amateur attempt at forgery
2. Burkett's lawyer says that Burkett didn't do it :)
Oh, I'm sure that he is the author, but I bet someone on Jenjis John's campaign delivered it to Rather. The MSM is now busy writing sKerry a get out of jail free card, and they are going to leave Burkett holding the bag. Too bad, so sad for Burkett.
Also they came from a Kinko's 21 miles from his home. What are the odds that there is another person similarly informed and motivated on this particular issue that close to the Kinko's.