Not my words, but a comment left at this link sheds a lot of light on this story:
"I was a bike monitor at the 2008 Sarasota Marathon..my first voluteer, although I am an experienced runner..biker..duathlon..
"I know personally Mrs. Nobles situation and why she was disqualified and relate the following..at +-16mile Mrs. Nobles stopped at a construction site port a let (on the course but on the otherside of the cones) and emerged moments later walking in the opposite direction with her bib #removed..when approached by two experienced bike monitors to see if she was disoriented, they were told she was "not feeling good".."it was a training run" and that she would "be fine walking back in"...they then picked up the 2nd female runner and escorted her thru the remainder of the zone, approx. 5m. The port a let was approximately 1 mile from the 17 mile chip pad..which Ms. Nobles failed to cross..as the person manning that station attested..the 2nd female runner did cross..the course returns from a short loop to that porta let site..Ms. Nobles must have rejoined the runners shortly after that point and completed the race in her typical times.The bike monitors in this zone where all experienced runners and bikers..but that is irrelevant..as the facts were indisputable..I'm sure she's a fine woman and experienced runner..but she made a quick and bad judgement..a low moment..she will learn from this..the RD of the race asked that the media be left out for Ms. Nobles sake.. and i.e. my anonymous posting"
Obviously, she tried the old "porta potty switcharoo" and got caught.
This shouldn't surprise anyone who's raced an IM before -- people try all kinds of crazy stuff there. Just swim one lap of the two, just run one lap out of two, etc. When those people get caught, however, they get banned for life.