America's Most Troubled Luxury Neighborhoods

In addition to the 10,500 properties already listed, there are another 9,500 in the wings, estimates Manhattan appraiser Jonathan Miller. Some 2,500 of these shadow listings belong to sellers who have some flexibility to keep their listings off the market in hopes of better pricing. Developers hold the rest. Both groups are likely to rush their listings onto the market once it's clear prices are falling.

Some folks can't wait. Françoise Pourcel, 62, listed her 2,100-square-foot Tribeca loft last August at $3.5 million, in line with the sale price of a similar unit on a lower floor of her building. In June she accepted a bid for $2.5 million.

Condo prices in Manhattan would have to fall 50 percent to return to values relative to rents they had in 1999, a relatively sane year in real estate. A condo owner could then lease his home and garner net rental income (rent minus property taxes, insurance and fix-up costs) equal to about 7 percent of the property's fair market value. The current yield is around 3.3 percent. Far too low.

It's a similar story in Lincoln Park, where single-family home prices slipped only 2.2 percent last year, far less than in the rest of Chicago. But inventory has since tripled. Wagner Appraisal Group figures there's a 16-month supply. A year ago "I was almost cocky about our position compared to the rest of the market," says Jennifer Ames. No longer. After 11 months of lowering the $2.1 million asking price on her 3,400-square-foot house, Ames sold it in June for $1.6 million.

Given the glut of unsold homes, Lincoln Park's prices may well slide at least 15 percent this year -- as Chicago's did in 2008. If you look at Fiserv data going back many years, you find values in Lincoln Park track the rest of Chicago pretty closely with a one-year lag.

In Santa Monica's coveted "north of Montana" area overlooking the Pacific, listings are up 60% since last year and the number of days on the market for those listings has doubled to 140. Homes once sold in as little as a week here. Closer to Main Street, Bill H. Meyers has struggled for more than a year to sell his condo.