We've been during Jersey Week several times. In 2004, the crowds weren't too bad Nov 1-2, but Nov 3-6 were quite heavy. We witnessed 90 min waits at many attractions in the MK on Nov 4 and ended up leaving the park around noon. Headed over to Epcot and found it to be a little better. I think this week is getting more and more popular every year.
I found this info here on the boards and I saved it for future reference in regards to the dates for Jersey Week :
2006
Thursday, November 9
Friday, November 10
Saturday, November 11
2007
Thursday, November 8
Friday, November 9
Saturday, November 10
2008
Thursday, November 6
Friday, November 7
Saturday, November 8
2009
Thursday, November 5
Friday, November 6
Saturday, November 7
2010
Thursday, November 4
Friday, November 5
Saturday, November 6
2011
Thursday, November 3
Friday, November 4
Saturday, November 5