An interesting article on Gamespot compares what the PS3 will have for an optical drive, Blu-ray, to what the Xbox 360 has, a normal DVD-rom drive, and asks the question: which one is faster?
My first thought was that the Blu-ray would cream the normal DVD drive, as it is newer technology and will hold more information per disc, but it looks like only faster 4x Blu-ray drives overtake their last-gen brothers. And since a 4x Blu-ray drive is too expensive to put in a PS3, it looks like only a 1x or 2x drive will be included.
From that you can draw your own conclusions, but it looks like jumping to Blu-ray might hurt the PS3, atleast in the short term.