I think it varies by state. I'm also not sure what happens in the case of a temporary layoff; I assume you wouldn't get vacation time paid out in that situation.
Mr. Smock got laid off earlier this year, and even though his company gives annual vacation time in a lump sum in January, the "company policy" is to only pay out vacation accrued by your last day, which meant he got less than we expected. The fine print always seems to screw the workers.
In other states, the company can do whatever they want. And even if it's written policy that they pay out, the policy is generally not legally enforceable, they can modify it whenever they want. It may create ill-will with the employees, but right now companies are doing what they have to in order to stay afloat.
Thanks, smock. I keep on seeing people say that they were laid off without vacation time and couldn't see how that was legal, but employees are getting screwed in so many ways.