You have received some great feedback both here and at dpreview. I cannot offer the expertise that so many others have as I am just getting started myself.
All I will tell you is to make sure you get your hands on the K10d before you make your final decision. As an owner of a K100d I can say I am a very satisfied Pentax user. Someday I hope to upgrade to the K10d for the many added benefits and features it provides.
While Pentax certainly is lagging behind Nikon and Canon in the number of religious followers they have (partially due to a smaller advertising/marketing campaign) I believe Pentax is gaining ground and is simply “flying under the radar” right now…which is perfectly fine with many in the Pentax camp. They make some great equipment and will soon begin regaining the respect that they once had back in the day.
And no question that Nikon and Canon do some things better.