The OU Guide to Pesach 2011 is here, and already people are complaining that it lists potatoes as kitniyos. In fact it does no such thing; in the article, on page 17, it specifically says that the traits of kitniyos "are not absolute, and certain exceptions are made, prohibiting items that do not share these characteristics, and permitting others even though they fall under these categories... it is customary to use potatoes and cottonseed oils (except in Jerusalem) despite the fact that they are ground into flour." But it is somewhat confusing and misleading that in the chart on the bottom of the page, it lists potatoes as a category of kitniyos.
I was more bothered by the article on shiurim on pages 12-14, which gave several different halachic opinions on the size of a kezayis, but gave the minimum as being 26 cubic centimeters. It's a pity that it didn't acknowledge the minimum as being 4-6 cubic centimeters, which, as acknowledged by many Poskim, and has no arguments against it that I know of, is actually the size of a zayis. If you haven't yet read my essay on the evolution of the kezayis, I can tell you that it's by far the most popular essay that I have ever written! If you have read it, please pass it around, it's free. You can download it here.
If anyone has the book with pictures of a kezayis of different foods, can they tell me if it has a picture of olives - and if so, how many olives it shows as being the size of an olive?