I’m sure this is stirring up a huge can of worms (where’d that phrase come from?), but is Cecil planning a “Nine Yards” follow-up? I searched for some sort of resolution on the boards but got nowhere.
To throw in my two cents (and that one?), I saw a documentary on WWII fighter pilots. One vet said the phrase originated with the length of ammo belts in the wing guns. To shoot at an enemy with all you’ve got means you gave him the “whole nine yards.” The vet could be wrong, of course.
It’s too bad no one can come up with documents from that era that contain that phrase, which wouldn’t be hard to do if it was used half as much as some old veterans claim. 
Welcome to the Straight Dope Message Board, ety3!
Another problem with the WWII-origin theory is that the phrase did not appear in print until the early '60s, in the context (I believe) of a Vietnam novel. Linguists find it very unlikely that a phrase of alleged WWII origin would not appear in print for some 20 years.
– Beruang
http://boards.straightdope.com/sdmb/showthread.php?threadid=70677
If you can come up with a cite in print prior to 1966, I will pay you $500. cash, US.
Disclaimer about my $500 offer*
*Odds of winning 1:gazillion; offer limited to the current decade. Members of my family, or Barry Popik, are not eligible.