Originally Posted by mattdm 
Cool — thanks for testing. Given that the Metz flash can get the ISO information, it'd be crazy if the Pentax version couldn't do something with it.
So, how exactly does it behave in Auto mode in Av or Sv?
Oh, and what does it do in Tv or P if you're using Auto ISO?
It looks like in Av nothing is automated. You can set aperture and the camera still picks shutter speed up to 1/180th but nothing changes on the flash and it will expose incorrectly. I don't have Sv on my K100D so I can't test that but the manual says only P and Tv in A mode. Auto Pict mode and all of the scene modes seem to work the same as P on my camera. You can use them but the camera defaults to what the flash is set to.
I tried to shoot with very small apertures to see if it would bump up ISO in Auto ISO but all I could get are shots at ISO 200. Looks like the K100D at least defaults to the lowest ISO for Auto ISO shots in A mode.