Moody's warning on the U.S. credit rating: A bit of payback?

Even since Standard & Poors warned Britain about its credit rating last May, I've been wondering when one of the credit rating agencies would take aim at the U.S. and its gaping federal budget deficit. Moody's (MCO) did just that on Reuters Television Thursday, when it said if the U.S. doesn't reduce its deficit spending to manageable levels in the next three to four years, its top AAA rating could be lost.