AF Fix Using Free Software
Barry Fitzgerald's review is spot on. Currently own the K2000 and the K-r is a vast improvement.
From the factory, the K-r front focusing was really bad (tested 3 lens: 18-55mm f3.5-5.6, 28-90mm f3.5-5.6, and 35mm f2.4). I had to AF Fine Adjust to -10. I then found a nifty app called PK_Tether, which allows you to put Pentax cameras (K-x, K7, K5, K-r, K20D, K10D, K200) into debug mode. That enables you to get to the Debug menu and do AF calibration. I am not sure what the max is but I went as high as -19. You would want to reset the AF Fine Adjustment to 0 before using the calibration. That way you can do fine adjustment from the calibrated setting.
Other than the front focusing issue, the K-r could use the individual AF fine adjustment setting for up to 20 lens feature available on the K7 and K5.