Argumentum ad Hitlerum is quickly becoming a formal entity that describes as childish any person who, in the absence of better reasoning, resorts to comparing someone she hates with Hitler.
Good point. It does come across as silly and childish. If somebody has an argument to make, it's more convincing if they don't automatically reach for Hitler analogies.
One big problem with this "Obama is a racist, Hitler was a racist, Obama equals Hitler" approach is that a lot of Americans in history have been "racists" by today's standards. Were they all Hitlers? That's an awful lot of Hitlers running around. Some of them have even been president.
As I said to gaslucas, no one is saying that Obama will go to the extremes that Hitler did. No one is saying that Obama is Hitler. Comparisons can be made between these two individuals’ view points though and the policy directions that Obama is taking. If this were one thing, where it was say just the nationalization of an automotive company, I would agree with you that it is childish. The problem is though, there are more comparisons that are valid than are not.