Does anyone know what happened to the company that used to build Carbon fiber wheels? Are they still around or did they go under?  

You talking truck or ATV?

These guys make ATV wheels, but I'm not sure about truck...

http://www.hiperracingwheels.com/  

I do not see much future in them as a wheel because though carbon fiber is strong for its weight it does best in a fairly narrow envelop of designed stress axises and limits. A wheel on a big 4x4 would see a very large envelope of stresses and unlike a steel wheel which will yield some and survive when its tensile strength is exceeded under impact loads, carbon fiber will break down and loose a LOT of strength when this limit is reached which can lead to total and rapid wheel failure.  

Yes, I agree, Carbon fiber wheels have a very specific purpose when it comes to 4x4s. Sand dune running is where I see a benifit. Heath Biggs had a set on his Scorpion for a while and said they worked bitchen. I wouldn'r run them in rocks. I'm thinking of putting a set of 46-inch paddle tires on the Mega Titan.