I've had two Generations of the Pentax WR series, and have been very, very happy with it. My newer one did die this summer, but I think that was because I took a hard fall on it and compromised it. My first generation one is still going strong after 5 years or so. If you look at my photos on this site, nearly all were taken with one of the Pentax camera.
I've looked at the Olympus, and it seems very sturdy and well built, but have no personal experience with it.
I'm going to be looking for a replacement for my 2nd Gen Pentax soon too, so I'll be interested to see if anyone has directly compared the two.
I just purchased the Olympus 850 SW with a floatable strap. My first h20 proof digital camera. I clip it in on a boogie cord in front of me. I also put on that scratch proof film. Using a h20 proof camera, sure beats trying to operate a camera's control from the outside of a h20 proof bag.
This camera has advanced controls for more advanced photographer and the video is a plus (Surprised how small the video files are(mb). Nice for emailing.