A conservative friend sent me an email of Obama's Top Ten Flip Flops, including taking money from special interests, waffling on illegal immigration, decriminalizing marijuana, NAFTA, handgun control, the death penalty, campaign financing, and the Iraq war. As every political science major knows, every politician running for president(except for Reagan in 1980), addresses their base in the primaries, then moderates their rhetoric to appeal to the center and capture a majority.
Unlike Obama, McCain finds himself stuck on the right, due to his recent conversion to right wing positions on abortion, torture, immigration, right wing preachers, and the Bush tax cuts. Maybe McCain has got religion and seen the error of his moderate past, or he is so desperate to become President he's willing to give up his maverick straight talking identity.
Obama excused his apparent contradictions by telling Forbes magazine that "sometimes during campaigns the rhetoric gets overheated and amplified. Politicians are always guilty of that, and I don't exempt myself."