I pitched 11 grams of Nottingham into my 1040 ale, when all the calculators I consulted (Mr. Malty, etc.) recommended 10. I figured, better safe than sorry.
Then, too late, I noticed that my recipe (from "Brewing Classic Styles," a batch that straddles the line between ordinary and best bitter) recommends 5 - 9 grams of dry yeast!
Subsequent reading warns me that by overpitching, I sacrifice valuable aromatics and esters. But is my 11 gram pitch really "overpitching"?