tedster - 2:25 pm on Sep 1, 2010 (gmt 0)
Absolutely yes, certain query terms are tagged to change the way the results work with the seasons. Others with the day of the week or even the hour of the day. It is also mentioned in one of the patents - I'll see if I can dig it up.
In fact, many recent ranking and traffic changes could be due to Google switching to "academic season" - and there are other season factors besides school that are involved with this time of year.