You should take the most you think you're going to get. The value isn't going to go up, and may well go down very quickly once a media event is scheduled if the major media outlets pick up on it and the general public gains more knowledge of an impending new model. i.e. try to sell it soon rather than holding out for an extra $50.
Search ebay for completed sales as a pricing guide. Remember also that you don't pay ~12% in ebay fees, so you can afford to underprice on CL for a quick sale to get it done with.
http://www.ebay.com/ccg/Apple-iPad-..._sticky=1&_trksid=p5360.c0.m299&_sop=13&_sc=1
Thanks a lot! That is very helpful!