This is something I've never seen before in my 12 years of wrenching on cars. For awhile now I've noticed my Accord losing coolant and have suspected a bad head gasket. It doesn't leave any puddles but I haven't noticed any coolant in the oil. However, today I noticed the weirdest thing ever. While trying to run the air bubbles out of the coolant system exhaust gas was literally blowing out of the radiator. I've also noticed that if I take the oil fill cap off there's a lot of hot air blowing out of it.

Are my suspicions correct that the head gasket's gone so far south it's actually headed north?

 

Exhaust coming out of the radiator has to be a headgasket problem. It can leak between the cylinder to the water-jacket, and not involve the oil passageways at all.

The feeling of air blowing out of the oil-fill cap might be normal or it might be unrelated. (since you say there's no coolant in the oil)