Read the two stories of the same person below, for the K20D and K10D respectively (and both with a DA* lens), then you will know:-
http://www.pentaxforums.com/forums/pentax-dslr-discussion/72794-just-share-stories-pentax-dslrs-water-resistance.html
The quick conclusion that we can draw is that the sealing of those "WR" Pentax DSLRs is not totally and completely water-proof, or not even weather-proof. And it is just nothing that can be compared to those truly water-proof professional workhorses of Canon and Nikon, which are used by all those outdoor photographers (say, photojournalists) in a variety of adverse conditions but their cameras (bodies and lenses) still works reliably to enable them to complete their jobs without any worry, concern and constraint imposed.
Update (10-6):
Here is an interesting video for showing how a K-7 is showered:-
http://www.youtube.com/watch?v=Op9mBbo92Ik
But it is told that his camera was eventually damaged and the "demonstrator" was asking for advice! ;-D