I stopped by Circuit City yesterday and checked out the XSi as I've been looking at that camera too. It's really not much of a "deal" there, they are selling it for $719 w/lens, down from $799. IMO your better off going online or waiting to see if they discount them further (if there are any left).
Pretty funny, those "liquidation sales" really aren't that much of a deal, since another company takes over and raises all the prices back up to MSRP and then discounts from there. That said CC was packed with people thinking they were scoring...