From FreeRepublic.com :

The bow in Japan is not , contrary to Western conventional thought, a gesture of submission. According to Japanese tradition, the human body has three "zones" . Heaven ( from the shoulders up) Man (from Shoulders to hip)and Earth ( from the hips down.) When one bows in Japan, one offers the highest of the body in respect, the heaven aspect. Obama is indeed as you say, prostrating himself, and Akihito Samma, is not bowing even a little, either because he i s surprised, or because he does not respect Obama.The real key is the empress, who is not bowing even a little.

They do not respect Obama enough to bow even a little.This is done with feeling in Japan, and is spontaneous.It is a thing involving a type of perception very different to Westernern cultural ettiquette. A genuine bow can actually be felt in the heart. And Akihito knows this bow is all show.No heart. That is likely why he does not return Obama's bow, even a little.Nor does the Empress. Obama , intent on being the skillful inter cultural president, shows here that he knows nothing of Japanese culture.Before one bows there is a brief glance at the eyes of the person to whom one bows, a spark. This is what Obama is missing, or they both would be bowing back.

Secondly, Obama should have bowed before he shook hands, in the proper way, with his hands on his upper thigh, and he should not have bowed so deeply, because he is not a Japanese subject... a slow respectful bow of 45 to 50 degrees would have been required in his case, if Obama knew the correct protocol, which he obviously does not. So it is a false submissive bow of a man who has little honor in the way of Japanese thinking. A man who wants something. A man not to be trusted.

Obama did not fool the Imperial couple even one little bit, and they are strained to remain polite, humoring Obama as it were. Patronizing conduct gets one no where fast in Japan. Generally Japanese folks know a genuine bow from a false one by the way it feels, a form of perception which few Westerners experience, but still some do.

Obama has idiots for protocol officers, or alteratively, he did not listen to what they had to say about it.

Obama would have been much better off simply shaking hands, instead of this empty, false bow, completely off in its lack of genuiness. The bow of a snake.

I predict that Obama will make little progress with his diplomatic agenda in Japan, he will give much, and receive little in return.

From FreeRepublic.com :

Bowing and violating US Code
Officer Training

11/15/09

by pabianice

When I went through Navy Aviation Officer Candidate School we were given classes on military etiquette. One lesson dealt with meeting foreign dignitaries and royalty. In a film and then with text we were instructed that US law "forbids any officer of the United States from bowing before royalty. Instead, if in uniform and covered, the officer salutes. If not in uniform, the officer shakes hands or simply stands at attention."

This lesson was very clear and I have no information to indicate that the rules have changed. The president, like every US military officer, is an Officer of the United States. Aside from the general embarrassment that Obama has become at home and abroad, he apparently is also violating the law with his bowing and scraping before foreigh royalty.