The rumor is that China is going to restructure its sovereign wealth fund, China Investment Corporation (CIC) to remove its bank holdings from its portfolio. About half of the CIC's 200 billion USD is in China's banks and if Beijing were to replace that with cash it would be in a position to buy into US markets in a big way. They are supposedly eying US stocks, bonds and real-estate. The CIC is currently restricted by the US Federal Reserve because of its status as a bank holding company.
If this rumor coming from the bankers in China is true it would pump up the US bubble economy considerably (it would do nothing for the real economy). But that is only if the extra cash coming in can overcome the selling stampede that is currently ongoing in the US markets. The markets would be in free fall except that the big Wall Street banks have unlimited Fed money to throw around to keep things moving their way.
It's not clear what is really going on with the CIC as it is also in the center of a bureaucratic turf war between the People's Bank of China and China's Finance Ministry over who controls the banks in China. It seems odd that China would want to invest in the US having lost half their money the last time they tried it. On the other hand if they are only doing it to settle a feud then they might do something uncharacteristically stupid. I wouldn't want to be one of people who pushes for this after it blows up on them.