There are parts of the US in which d/m/y is more common, as well. In Florida, in particular, (although I'd expect Texas, Arizona, California, Lousiana, and probably Vermont and the Dakotas, if my ethnic stereotyping classes were correct) this is a constant problem. If M/D/Y were so popular, the IRS wouldn't have to print "month" and "day" on their forms.
Besides which, almost all US institutions of any size -- federal government, military, large corporations, hospitals, &c. -- universally use y/m/d for their short form. It's even becoming standard on movie posters, and I've seen more than one 2001 wall calendar printed that way.
IMHO, the only place in which it isn't just plain rude to use M/D/Y is if it's plainly labelled as such, or when the month (or possibly even the day) are written out: eg. January 01, 2001, or January the First, 2001.