The repurcussions of foreclosure individually are: 1) your credit report is dramatically lowered, and it will be very difficult to get another mortgage in the future. 2) Even after the lender has foreclosed, they often still have the ability to put a judgment against you, which can lead to garnished wages, and will keep you from being able to purchase other real estate. 3) If the bank does not go after you through a judgment, they must report to the IRS that the they "forgave" the debt (if your house was not worth as much as your mortgage debt), and the IRS considers that to be income, and will tax you on it.
But, as of early 2008 (or so), the taxable income (loan forgiven) is non taxable.