American forces in Japan are currently in a state of flux. Unlike South Korea, reductions in the number of American forces stationed in Japan were not envisioned as part of the Global Posture Review.
It does appear, however, that the number of Marines stationed on Okinawa will decrease. Almost half of those men and women will be relocated to Guam and others to another base on Okinawa (thus allowing the closure of one Marine base on the island). Both moves will please the people of Okinawa, who unlike their countrymen on the larger islands, would generally prefer to see the Americans leave town.
Less likely to please the locals is the recent announcement that the United States will bring home the USS Kitty Hawk (CV-63) (which currently proudly wears the designation of being America's only permenantly forward deployed aircraft carrier). It will be replaced by a more capable Nimitz-class carrier. Defense experts have long seen this day coming, as the Kitty Hawk is the oldest ship in active service in the US Navy and is due for decommissioning in 2009. The reason that this is significant to many Japanese is that the Kitty Hawk is non-nuclear. With the exception of the Kitty Hawk and the USS John F. Kennedy (CV-67), all the rest of America's carriers, including the Nimitz-class carrier that will replace the Kitty Hawk in Japan, are nuclear. The Japanese government has given its go-ahead but protests can be expected.
As if this wasn't enough change for the military posture of Japan and the US forces stationed therein, the ruling Liberal Democratic Party (LDP) has just endorsed revisions to Article IX of Japan's Constitution. For those of you not familiar with the article, it is the one that prohibits Japan from raising a military. (Yes, Japan currently has a substantial military, but it is called a "self-defense force" and that seems to fool some people.) This will likely lead to mass protests in Japan and China (possibly South Korea as well).
Update: This Asahi Shimbun article says the locals feel this deal is leaving the wrong Marines on the island.