I believe Theta has announced June of this year. However, this is not just Dirac, but also on upgrade of the DSP processing engine from 48/24 to 96/24 or 192/24. The upgrade will be delivered through a field installable new board - pricing will be $4,000 for CBIII HD owners. It all strikes me as a fairly significant piece of engineering, so seeing is believing. There is a lot of excitement on the forums about this project though.
Since it was going to cost me $10,000 to get to HD and another $4,000 to get to Dirac and everything else, I passed. A year from now I may be kicking myself.