I got the Canon 40D. I had been waiting until the price of an SLR with a "full size" CCD sensor dropped to under $1,000. I have some old EF series lenses from an EOS 630 that I had some years back and wanted to take full advantage of the investment in them.
The 40D doesn't have a full size sensor equivalent to the 35mm film format, the 5D does. There's a 1.6X conversion factor. The price of a 5D that I wanted came down but remains higher than I want to pay. I also had gotten to thinking about how I use and enjoy photography now. It's different from earlier where resolution drove my hardware selections. Today I mostly view images on a computer screen. The advantage of the additional resolution that a full size CCD sensor gives (+12 megapixels on a 5D to +10 megapixels on a 40D) mostly pays off only when one prints or wants to shoot very wide. I hardly print at all now and when I do, 8x10 is about as big as I would intend on displaying. The smaller size and weight of the 40D, option of using less expensive EF-S series lenses (very wide is pretty affordable), and a load of other technical features above the other Canon digital SLR models were enough to convince me that it was a better choice for me and time to go ahead. I anticipate that Canon will release another model before Christmas but with the low value of the dollar today, the price will probably be prohibitive too.
I used the 40D today a little bit and the difference was immediately noticeable to me. I could shoot wider than my point and shoot digital camera, use telephoto to put the focus on subjects properly, and perhaps more importantly, I could time the shooting of the image to the right moment. With a point and shoot, capturing Max when he was doing something interesting was hard because of the delay of slower processing. The 40D seemed to react when I wanted it to. I didn't have time to take many action shots today but will try that later.