Originally Posted by Greg Rempe
...Perhaps he meant over other material that grill grates are made out of...
3 Olives, personally, I would not opt for raw CI because if you are not diligent at cleaning them and seasoning them often they will rust. Another option is porcelain coated cast iron which was very popular a few years back...Weber makes them for their gas grills but not the kettles. CI or PCI hold heat better...I'm not a believer that they give you better grill marks...I switched my PCI grates out to stainless steel on my gasser and still get grill marks that look fine...and the maintenance on them is easier and I can use a big broiler brush to clean them off without fear of chipping the PCI coating.
In the end, like everything with bbq & grilling, there is no right or wrong answer...it's just what works best for you. I have a CI grate in my Bubba Keg (that's what came with it) and I hit it with PAM after every use and it hasn't rusted yet...but you need to be good about the seasoning of them or you will loose that battle of the rust!