Porridge and a banana, about 2.5 hours before the start time. Plus a cup of coffee and a pint of water. Then no liquids at least an hour before the start, piss out as much as possible, and a few swigs of Lucozade right on the start line.
That's the textbook version. When I did Paris I didn't quite manage to sort out my porridge strategy at the hotel, so brekky was half a roll, a coffee and some orange juice. Still made my target with a negative split though.
Bottom line - probably best to do what you normally do for a long run. The most important time for fuelling before a marathon is when you're carb loading - a couple of days out and up until early the day before is best, IMO. If you get that right, along with the taper, your glycogen levels will be about as good as they'll get, without race day brekky being much of an issue.
Edited: 15/03/2012 at 17:08