It's a combination of
1.) Wealthy Asian businesspeople who are looking for a place to park some of the foreign reserves they own overseas.
2.) Hedge funds, investing institutional capital in relatively "safe" investments with guaranteed revenue streams.
3.) Corporate prop-trading desks, parking corporate profits in tax-advantaged long-term assets until its needed. Google, for example, is a major owner of affordable housing developments.
This is what often happens after a speculative bubble bursts: all the folks who invested based on irrational exuberance get cleaned out of the market, and then assets are transferred to other investors who are generally much more prudent, often using spare cash that was sitting on the sidelines. In this case, the assets just happen to be where everybody lives.
Very interesting as Google will be expanding their offices in Boulder over the next few years. I believe they've broke ground on the campus here.
