Oh, look at what I found: Pre-race and post-race day tips for half marathon and marathon runners.
It's a good article for anyone considering increasing the length of their runs. I particularly think the "nothing new" concept is very important and holds true for any type of training. If you have trained wearing a certain pair of shoes, clothing, socks, etc. and you follow a particular routine, deviating can be a real blow to your performance and your mental state.