Apple is apparently going to give the App Store approval staff some time off over the holidays. But don't worry, you'll still be able to shop. It's just that developers who are rushing to get holiday-themed apps into the App Store will need to make sure that they get their content approved before the holidays arrive.
According to Macgasm, the content lockdown has occurred at Christmas in the past. This will be the first year that Apple is throwing the Thanksgiving holiday in late November into the mix as well, ensuring that the App Store folks can get their fill of the U.S. Thanksgiving feast and watch lots of college and pro football. Developers won't be able to make changes or submit new apps during the lockdown periods through iTunes Connect, the portal that devs use to coordinate app entries in the store.
There will also be a freeze in the Top App listings during each of the holidays, so developers might want to make sure that they're at the top of the heap before taking a short vacation -- they'll get a few more days of App Store listing love that way. Developers are also reminded to pre-schedule any price changes during the freeze, as they won't be able to adjust pricing for special sales during the lockdown.