It was generally assumed that the PlayStation 3 would be using a 1X drive, untill Josh Peterson, Director of Strategic Alliances, Optical Storage Solutions, Hewlett-Packard Company made a few comments regarding Blu-ray.
"The read speed of Blu-ray is something that drive manufacturer's specify, and it will vary from vendor to vendor. The only thing specified by the BD spec is what the "1X" speed is, which is 36Mbps in the case of Blu-ray Disc. We know that some of the first generation BD drives will be "2X" for Blu-ray Disc Data Reading which is 72Mbps."
So If 2X drives will be available at the launch of the Blu-ray format, Sony might decide to install 2X drives in PlayStation 3, cutting loading times in half. Or even better a 4X Blu-ray drive, cutting load times even more.
Source: IGN