On October 10th the leaders of Japan, China and South Korea gathered (such gathering is already the second) in Peking. Japan's new premier Mr. Hatoyama proposed that all three countries pursue the idea of establishing an "East Asia Community" as a long-term goal.
At the meeting Hatoyama began his statement with the words (according to Asahi newspaper), "Up to now Japan has been rather too dependent on the U.S. While I continue to attach importance to Japan-U.S. alliance, I want to promote a policy in which Asia will be given more importance than before."

These two things might be over-interpreted as Japan's attempt to form an East-Asian bloc. But things are not that unequivocal. And here are my off hand comments.

1. This Japan-China-South Korea forum is a very mighty economic grouping (It does not have any institution, though. It is exciting to note that President Li of South Korea proposed to establish a "Cyber-secretariat" for the forum.)
But one has to note that these three countries thrive thanks to their symbiotic economic ties with the U.S. It would not serve their interest to exclude the U.S. from Asia.
These three countries are well aware, too, that the political and military presence of the U.S. is the cornerstone for the maintenance of the status quo in their region.

2. This tripartite gathering is an embodiment of friendship and cooperation among three big powers, the relations between which have been often torn with historical enmities. It is the U.S. has always been calling for a mutual understanding and concord between the three.
Friendly relations between the three countries reduce the risk for the U.S. to be entangled in conflicts among three countries.
In other words Mr. Hatoyama may well want to reduce such risk and burden (in his own words "Japan's dependence on the U.S.) for the U.S.

3. As regards America's involvement in Asian affairs, one has to note that the U.S. is member in a variety of forum; for example it will host the APEC summit meeting in 2011.

4. Besides, however, it is time for the U.S. to streamline the form for its involvement in Asian affairs; East-Asian Summit meeting, the six-party talks on denuclearization of North Korea, ASEAN Regional Forum (ARF), the Shangri-la Forum and so on.
Things will be sorted out anyway toward Mr.Obama's visit to Asia scheduled in mid November.