Nothing new, but still awesome. 5.0 swaps have been around forever. On the other hand, there has been a couple of LS1 Miata finishing up, and I find that to much more appealing than the 5.0s. There has been the FC20 swaps (S2000), and I think someone had a SR20DET too. 5.0 is the most common one though.
Regarding the Rotary Miata, some guy over here brought a Rotary Miata (Twin Turbo B13 from an RX7) out to a local autocross event. The thing sounded absolutely wicked and launched like a bat out of hell. Quite possibly the loudest blowoff valve I have ever heard. The driver was pretty good, and it was a very quick car overall. Not a bad idea for a swap, but a few issues.
Forced Induction Rotary reliability is always low, and maintanence costs are always high when you have to rebuild the engine constantly. Expensive and difficult to get, espically the TT B13 from a FD RX7 (well, when compared to a much more common 5.0). Simply put, there is a much larger supply of 5.0s available that fit just fine and perform just as well for much cheaper than a Rotary Swap would cost. Then there is the issue of burning oil, bad gas mileage, and lack of torque. While a cool and high performing swap, in terms of practicality, the 5.0 is hard to beat, and the B13 is on the bottom of the list.
Regardless, all engine swaps are cool, and I bet that 92 is QUICK.