The GPU/CPU are what produces the image displayed on the machine, so not really. mostly texture quality is determined by the memory available to the GPU.
I've heard of texture streaming of the disk, but it reads a lot slower then off the ram, so you get a pop-in effect I believe.
Most games haven't really been pushed datawise on a DLDVD so there won't have been any need to compress the textures for the DVD.
The main advantage of blu-ray with graphics is just you can have more textures on the disk or higher resolution, but as said unless you have the hardware to render these. it makes no difference.
An example would be. say your looking at a single room at a time, you could have each room having a different texture which would make the game more diverse, then having every room look the same, but if you could see lots of rooms at the same time, all these textures would be too much for the GPU to display.
Thats how i understand it would work anyway
X2 blue ray isn't quite comparable to X12DVD, so to say 6times faster.
Blu-ray 2x: 72Mbp / 8MBps
12x DVD: 66 - 132Mbps / 8.2 - 16.5MBps
source http://uk.gamespot.com/pages/profile/show_blog_entry.php?topic_id=23916169&user=skektek
Edit:
ps3 is stuck with 256 system and 256 video memory. 360 has 512 unifie
I believe the PS3 GPU can use the system memory as well? the 360 also has the 10MB of embedded memory, which I believe helps alot.
