From The Wall Street Journal:
Delinquencies have shot up in recent months among prime borrowers who had sound credit as white collar job losses mounted. Financing for jumbo loans, which are too large for government backing, have become harder to get. And with home values falling across all types of housing markets, refinancing is now out of the question for jumbo borrowers who aren’t willing to put more cash into their homes. Move-up buyers aren’t there, in part because it’s tough to get financing. And many jumbo loans are resetting to higher payments, including those that carried “interest-only” terms for an initial five-year period.
It should be noted the above Journal report was about the state of California. Boston and the Northeast was NOT mentioned in the article.