Even though Apple's compatibility list does not include _any_ Pentax camera, I can tell you it works fine with my EI 200. I held off downloading iPhoto for quite a while because my camera wasn't on the list! Even tho' Apple _says_ the list is updated regularly, I've seen no change lately.
[Editor's note: They are updating the list at least occasionally. My Canon PowerShot now shows up, but it wasn't there when I bought the camera a month or so ago.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20020218205100891