I was actually trying to get a picture of all 3 cats together. I was waving a toy above the camera to get their attention and didn't even notice he had his mouth open until I looked at the screen (taken with a digital camera). I don't think he was yawning, actually I'm not sure what he was doing.
Sicycat - I loved that thread, unfortunately I haven't been able to stop yawning since looking at it. It really is contagious!