I'm interested as well. I have your USB Tellstick now and I'm very happy with it.
I also just bought an Arduino UNO and would like to be able to talk RF with that as well.
I was thinking of being able to move the antennae off the board and mount them on the outside of a box. I guess a shielded extensioncord could do that. In that case a detachable antenna (screw mount) is imperative.