I've always rested meat for about 15 minutes but was watching Jamie Oliver yesterday and he rests his for an hour.
I can see that's handy for freeing up the oven but doesn't it mean the meat is cold when you serve it? DH doesn't like gravy so it can't be heated via that and we don't have a microwave. Interested to know how long you rest your meat for and if it's cold when you serve?