Not sure if anyone else has run into this, but it's driving me up the wall.

I'm still in development so I don't see actual ads, just the placeholder [mobclix.com] ones. But like I said, only on my Touch and my iPad. Is there something special with iPhone I need to do?

The issue was the fact that it's a retina display, so my math using screen.width wasn't actually correct. As Mike from Prime31 put it:

The issue is most likely due to Unity reporting screen coordinates in pixels while iOS uses points. If you are outputting to high res for retina screens you will need to do ( Screen.width / 2 ) / 2 when on hi res, or just ( Screen.width / 2 ) for low res.

Good to know.