is the black granite color on the malibu the same color as Carbon flash on the aura and G6, just a different name?

Most likely. GM tends to do that with paint colors across the different divisions.

Absolutely, yes. This color has spread across most of the line, now.

Names include Black Granite, Carbon Black, Carbon Flash, and now for 2009 Cadillac also offers it as Black Ice. Same color, all around, just different names for the different brands.