I have the K10D. I bought it after trying to decide between the Rebel XSi, the K10D, and the D80. I chose the Pentax because it fit me the best, the quality was by far the best, plus the weather sealing, and in-body IS which works on any lens, including the long line of older MF lenses available for cheap. The twin control dials, Hyper-manual, and top mounted LCD added sweetness to the deal.
If you shoot sports, and need really fast AF, the K10d might not be your best bet, but I love mine, and have had no regrets on buying it.
RD