I did a bit of research, and there is a 'slim' 9.5mm model of slot load DVD/RW drive that burns DL DVD's. It is a Panasonic (Matsushita) model UJ-842S. There is also an older model UJ-832S that is also a DL burner. The problem with both of these drives is that they are hard to get(and they're expensive). The UJ-842S seems to be built for IBM laptops only. I guess my point is that there was at least one model of Dual Layer 9.5mm DVD drive available to Apple when the MBP's were built. So why didn't Apple install them in the 15" MBP's? The other point is that if these drives exist, one would assume that more models are to follow in the future at (hopefully) reduced cost.