There has been considerable debate since last month's historic North-South Korea summit about the meeting's impact on the peninsula's neighbors and benefactors. The conventional wisdom seems to be that China fared best. However, I would argue that all four major powers have come out ahead and that the United States, Japan, and even Russia may end up gaining relatively more in the long run. If managed carefully, the summit process can result in a multiple "win-win" outcome.
China: China has been - and should be given credit for being - an effective facilitator and interlocutor between the two Koreas. The secret meetings that helped set up the summit were hosted in Beijing, and North Korean leader Kim Jong Il's highly publicized (after the fact) visit to Beijing demonstrated the continued close relationship of these two allies. Beijing has, in fact, taken many steps over the past several years to position itself as a trusted friend of both North and South, and its stock has clearly risen as a result of its presumed behind-the-scenes role both in helping to bring about the summit and in moderating the North's behavior.
If one accepts that China's long-range goal is to replace the U.S. as the security guarantor on the Korean Peninsula, however, then the summit was not all good news for Beijing.