Will you/did you upgrade to the 30D or the 40D?

I went from the 20D to the 5D and haven't regretted it for a second. Although it is fun to think of owning a 1Ds mkIII if I spend any more money on photography I will probably put it into glass. For me most of the improvements to new cameras are incremental rather than truly novel (and many such things, like print buttons and live preview, are not of any use to me). I still use both cameras and am more interested right now in improving my abilities rather than buying more gear.

Thanks to you all for a fantastic response!
For me it will be a refurb 30D up from a 350D
to save money for glass.
I want the higher ISO performance and higher fps
of the 30D, both for indoor sports.
And I figure if I want more fps and megapixels in 6-12 months
the 30D won't lose too much value and the 40D will come down a bit.
Thanks again.
Good shooting.

I progressed from 400D -> 5D -> 40D(x2)

I love them all; they all have their strengths and weaknesses particularly related to the type of shooting you use them for. I will say this though: The 400D/Xti was my first DSLR and I will always be attached to it in some weird way. My other hobby being firearms collection/shooting, I'd compare the 400D to the AK-47. As long as the shooter is competent, it has everything you need; nothing more, nothing less. No need to worry about excessive cost, maintenance, etc. Good stuff.