"Most favored nation" is actually something of a misnomer, depending on how you define "most." Being a most favored nation basically means that the country granting you MFN status can't give anyone else better trade priveleges without extending them to you as well. Simple. When some ugly Americans hear about the People's Republic of China being MFN to the United States of America, they immediately freak out and wonder "Why do they get to be our best trading partner when they're commie buggers?!" No, no: it's not like that. China's MFN status only means that it gets the same sweet tariff cuts that the countries in NAFTA and the EU do.

The United States currently has MFN agreements with most countries in the developed world, with the notable exceptions of Japan and France, who have capped imports and thus forced the USTR to do the same (or the other way around, depending on which side of the fence you're on). Many Western European countries have MFN agreements with countries in the developing world, something that the US doesn't really like to experiment with, presumably because of the possibility of capital flight. The PRC is an exception, possibly because they are quickly moving out of their developing country status and entering the world of capitalist plutocracy like everyone else.