Well, it seems as if a number of people in the media have decided that Obama was fibbing when he said that some millionaires pay lower tax rates than their secretaries  because, as the usual suspects triumphantly declare, on average millionaires pay higher average taxes than middle-income Americans.
This is, of course, stupid: the operative word is SOME.
Turns out that if you look at the details, roughly 1/3 of the super rich manage a tax rate of less then 15% and most manage less then 20%. Super rich here being the top 400 house holds in the US. Buffet clearly lands in that that category and could be paying less percent then his secretary even if his secretary is only paying 15%.
In a sense, Obama didn't put his lower limit on the "Buffet rule" high enough. The range he picked included the highest paying Americans, those on the bottom end of the wealthy range.
Jay