You mentioned that you were wanting to get an additional lens. If you were to buy a lens off of the rebate list, you would get to double the rebate on both the 30D and whatever lens you choose. Or, you might consider buying a flash such as the 430EX. Then instead of just a $100 rebate, you'd get $220 back. You'd essentially be getting the 430EX for $20. I think most people here would agree that an external flash is a must. The built-in flash units are fine for an emergency but leave a lot to be desired in most cases.
The problem is that I whichever camera I go for it is a big expense for me. This is not what I do to make a living and to me this is a big purchase. I would love to take advantage of all the rebates and buy a camera and a few lenses and a flash but in the scheme of things I am barely going to be able to leave with the camera w/kit lens and a CF card.
So the 'small' amounts of money everyone mentions adds up to big doallrs for me. This is all about money for me but I will not compromise and will wait until I can afford the right camera. If I did not have to think about cash I would go out and buy a 30D today. I hear and read great things about the 400D and I bet I would be absolutely thrilled with it but I do wonder how long that will last.
Before I got my A620 I had limited understanding and experience with photography. Within about 6 months I was using the camera in M mode almost all the time and knew I wanted additional lenses. I was slowly outgrowing the camera. Now, another 6 months later I still love my A620 but am well aware of all it is and is not and I know I am ready for DSLR. I have a funny feeling that some of you that are recommending the 30D over the 400D are right in that the 30D is a camera that I will probably not outgrow. I really should go to the local camera store and feel them both too. Many refer to build and weight of the 400D as something they are not thrilled with and I can't relate to it because I have not held the camera in my hand.
I know I will wait at least until the rebates begin before I do anything so I will drive myself nuts for another few weeks and then more than likely just go for the D30 since I can see I am already presenting a good case for getting one.