Nice comparison.
Apart from the dust-proofing and weather proofing - which I've found in the past only provide a limited amount of protection, the 450 looks like a pretty good deal for the price.
What's lacking on the 450D compared to the 40D in my mind isn't that significant. It would be nice to have the sRaw feature for file saving.
The higher resolution files, and lower price mean I suspect I'll go out and get the 450D instead of the 40D I was planning on.