I have used a few of the new 39 and 70W ballasts designed for T6/PAR ceramic metal halide lamps. They have the size and look of a CFL ballast. They were great to work with and I'd use them again. Only poblem is your lamp lead length is very limited, so be careful w/ remote ballasted fixures. The old core and coil ballasts seem very old fashioned these days. I think eventually they will go the way of the magnetic flourescent ballast, relegated to home depot fixures. Now if we could only phase out the T12 bulb!
I believe the units I dealt with were form Advance:
http://www.advancetransformer.com/products/hid-electronic.jsp
