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At this point, it’s no great journalistic feat to report that home prices have fallen off a cliff.

The above map from IHS Global Insight’s 2008 fourth quarter housing report shows that “extreme overvaluation” now is a thing of the past—-except for, oddly enough, in Atlantic City, NJ (full explanation not provided in the report).

The slump has recently hit previously untouchable places, like Manhattan (In the first quarter of 2009, sales of co-ops and condos dropped nearly 60 percent from the first quarter of 2008. Average co-op prices fell as much as 24 percent in the same period, according to the New York Times.)

Thus far, I haven’t seen such reports about D.C. proper (a real estate oasis compared to other battered areas in the region). But stability differs greatly from zip code to zip code in the city. This weekend’s Washington Post real estate section included a story about how people are struggling to determine what’s overvalued, and what’s on target.

One source offered up an interesting assessment strategy:

“The way we determine whether or not we would buy a place is more looking at what the value of the house was in 2003, because it just seems somewhat ridiculous that prices went up as high as they did.”