I was browsing the pentax-slr forum over at dpreview.com, and somebody had posted a way to enter the "secret" debug service mode on the camera by pressing a funky series of buttons to adjust the focus point compensation. My K10d had some backfocus issues (as with all pentax cameras it seems) with some lenses, and it was so bad with the 35mm prime that I gave up using it a while ago. Guess what, I dialed a 50 micro meter adjustment to compensate for the backfocusing and now my 35mm prime focuses perfectly :-) All the other lenses seem to focus more accurately as well. I am in heaven.
The next step is to get a split-image focusing screen for those times one needs to focus manually, and I'll be set. I love the old-school split image focusing, and it'll be great to have that together with autofocus, which finally works the way it's supposed to ;-)