Skywatcher had a very good question about holidays in February that might affect a WDW visit.
I just printed out the following information from timeanddate.com. You can customize the calendar to include many different types of holidays--or none!
Remember, various states and school districts will have additional holidays.
January 1, 2009 New Year's Day
January 16, 2009 Lee-Jackson Day (Virginia only)
January 19, 2009 Martin Luther King Day
February 14, 2009 Valentine's Day
February 16, 2009 President's Day
April 12, 2009 Easter Sunday
May 25, 2009 Memorial Day
July 3, 2009 Independence Day (observed)
July 4, 2009 Independence Day
September 7, 2009 Labor Day
October 12, 2009 Columbus Day
October 31, 2009 Halloween
November 11, 2009 Veteran's Day
November 26, 2009 Thanksgiving Day
November 27, 2009 Black Friday (massive shopping day)
December 25, 2009 Christmas Day
If anyone notices any errors, please let me know and I'll correct them. :)
Added the Lee-Jackson holiday and Black Friday, which is the day after Thanksgiving. For the uninitiated, it's a massive shopping day that theoretically puts many retailers "in the black" for the year. Not everyone is off that day, but a good portion of the US population is, so it's a significant factor for booking Thanksgiving weekend.