^Pretty much spot on.
- the 450D also has a higher max iso I think 3200 isntead of 1600
-the live view system used in the 450D is apparently quite slow compared to the system that nikon has gone with, so it is only useful for certain applications, not like a digital compact.
- not all the kit lenses are IS, at least they aren't here in nz. we have kits bundled with the non-IS lenses from the 400D.
There are also other changes such as a larger view finder etc.
I just bought a 400D two days ago, I got it at a super good price with the standard 18-55mm lens, saved over $1000 on what I was going to pay for the 450D. I decided that I would be better off buying a better lens than the kit lens and some other accessories rather than having the latest model.
for a pretty comprehensive review of the two cameras, and then make the call as to whether you will benefit from the new features or if you would be better saving some $$. Also go into a shop and see what the cameras are like to hold, the 400D is slightly smaller and has a different grip to the new 450D. Some people with larger hands have found the grip on the 400D to be a bit too small for comfort.