The chronological option on Memento only appears on DVD region 2 discs. It isn't on the US R1 version, although a special edition is going to be released in North America in a couple of months. I expect this DVD will have the feature. My guess is, you'll also get a commentary by Christopher Nolan.
PS I am totally with you on the chronological issue with the Godfather films, Geoff.
"I know it was you Fredo. You broke my heart. You broke my heart."
"Mio padre se chiamo Antonio Andolini, e questi รจ per te!"
