I’ve been looking for the exact same thing for some time, but no luck in my months-long search. Microsoft, Logitech, and Apple all make quality Bluetooth keyboards, but sadly none have the split-key form factor. Microsoft and Logitech just announced their fall line of peripherals too, and no ergo BT keyboard there either. In the meantime, I tried the MS keyboard, but it was a bit laggy and I went back to a regular RF wireless MS keyboard.