Just read an article on ZDNet about researchers at Stanford coming up with a way to transmit and receive with the same radio at the same time.
I guess the key is the put a receive antenna precisely positioned between two transmit antennas. The idea is that the waves from the transmit antennas will cancel each other out and the receive antenna sits in the null zone. I wonder what the radiation plot is for that antenna arrangement, hah.
Here's the video from the article:
They are talking about applications for wifi. Could be useful for ham radio?