As I did read in the pdf's of Pentax then it sounds that the K20D will be an great upgrade of the K10D. At first it do not sounds like an big upgrade, but for me it sounds that this camera is more made for the photographer then the K10D. The quality of the photos sounds like one of the biggest isues of the developers. Not doing an race for getting an high as possible frames pro second... for most photographers is that not interesting. And if you need it, then there is a burst mode...
And more options to make photos on the style you like.
With the quality of the photos, the SR, an nice dust removal system, wheather resistant and liveview will make the K20D an very competive camera! We must be proud on Pentax to make a camera like this!
Let's talk now on the K30D, 645D and the K1D.