It seems like Canon can't give money away fast enough! In addition to the current round of rebates on the EOS 40D, EOS 5D and selected lenses and speedlites, and in addition to the extra discounts you get when buying a 5D or 40D with a lens kit and/or printer, Canon are now offering an additional $50 to any current owner of an EOS Digital Rebel, XT, XTi or XSi who registers their camera and buys an EOS 5D or 40D before July 19th 2008.
This brings the price of the EOS 40D down to under $900 and the EOS 5D down to around $1850.
Here's the link to the Canon rebate form: http://www.usa.canon.com/app/pdf/Promotions/40D5D_Promotion_May08.pdf
This now makes the EOS 40D less than $100 more expensive then the Digital Rebel XSi for those upgrading from a previous Digital Rebel body ($900 vs. $800). This is not a bad deal at all. While the Digital Rebel XSi is a very nice camera indeed, and has 12MP vs. the 10MP of the EOS 40D, the 40D is clearly the better built camera, with faster frame rate, a larger buffer, higher ISO settings and a number of other features which are detailed in my comparison of the XTi, XSi and EOS 40D. I'd consider the 40D a better buy at $900 than the XSi is at $800.