My current employer is a medium sized call center with IPCC Express used for their contact center solution currently. I'm still learning my way around UCCX but I'm getting there, I can program basic scripts and troubleshoot basic issues. We use over 40 different queue scripts that all calls out to the same default holiday script. This script then points to a very simple XML file that lists calender dates that is edited with notepad. If the holiday condition is met, the original script then inputs the variable set (usually set to change to the "closed" setting).
There was one queue that was supposed to be open today (oops) so I had to create a duplicate script called "holiday_Alternate" that called out to a similar XML file except it didn't have today's date (11/26/2010) listed therefore the original queue script was set to open instead of closed.