According to Peter Garber of Deutsche Bank, the ongoing support of the dollar by the Chinese is largely about export-led growth, to lower unemployment and underemployment among the portion of their population still trying to emerge from third-world conditions.
A less charitable (and generally free-trade-favoring) man than myself might interpret this as "they're literally buying our jobs". I'm not quite that upset about it, but it still does make me wonder whether this means that instead of having a big dollar slide in a year or two (something that seems like it ought to have happened a year ago, actually), we're really going to see a HUGE dollar slide in ten or twenty years, when it would be simultaneous with the retirement of the Boomers. Talk about a meltdown... The US would be turned into a third-world nation overnight.
Either way, the Chinese Yuan sounds like a good investment. It seems unlikely that the Chinese economy can actually grow fast enough, forever, to continue pegging the exchange rate by buying dollars. And even if it could, sooner or later it'd cause the US economy to tank so thoroughly that there'd be nothing for them to invest in by buying those dollars. Stein's Law: "Things that can't go on forever, don't." A big buy of Yuan today is likely to go up by 15-20% within the next decade, or by 150-200% in ten to twenty years.
If Shrub gets removed from office and US fiscal policy returns to something resembling sanity, this prediction might be voided... But the Rs in Congress will probably keep working to bring it to pass. :-P