travelin_cat - 7:10 pm on Feb 20, 2012 (gmt 0)
About two years ago we removed the sitemap on our site of approx. 11,000 pages, 10,000 of which (approx.) where forum posts. Never saw a hit/change to any of our traffic.
I was reluctant to remove it, but it had become unwieldily. So we did a bit of research that pointed to the fact that there really is no need to have one if of you have good site architecture combined with thorough interlinking.