These borrowers owe more on their homes than the home is worth. In other words, they'd have to bring a check to sell their house - usually you receive money when you sell.
A study by First American CoreLogic shows how falling home prices have brought more borrowers into trouble. Some of the trouble is from high risk negative amortization loans, but a poor housing market is increasingly bringing borrowers down.
The housing market (and it's effect on borrowers) has been especially harsh in a few markets. Without loan modifications or an improving economy, the problem will become more widespread.
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