I couldn't find this year's dates, but found this for 2008 on allearsnet:
Upcoming peak times that will see the seasonal price increases are:
November 22 - November 29, 2008
December 16, 2008 - January 3, 2009
April 5 - April 18, 2009
May 24 - July 11, 2009
I would think the dates would be similar. You just need to compare a 2008 calendar with this year.
You can also call Disney Dining to get exact prices during your dates.