In this thread I talked a little about the XBox 360's desgin being built around EDRAM utilization, this imposing bottlenecks for dealing with high resolutions.
I also talked about how on the PS3 it's possible for the GPU to use XDR memory to increase texture memory as well as texture bandwidth if needed and earlier I talked about how texture streaming can improve things as well, relevant to this here's an older Insonmiac quote with regard to texture streaming regarding to Ratchet & Clank: Tools of Destruction:
"Ratchet & Clank on the PS3 uses texture streaming which allows us to get about 150 MB of extra VRAM in each level
. This allows for much higher resolution textures than we used in Resistance, as well as more texture variety."
Obviously Blu-Ray disc provides benefits with regard to heavily streaming games engines (mainly 7.1 audio and high resolution textures), there's far more storage space available on mutli-layer / single-layer Blu-Ray discs (the amount of data that can be streamed). The constant read speed of Blu-Ray disc is an advantage, a great benefit in this regard and makes this far more predictable for games developers, this constant reading speed is also faster than the average reading speed available to dual-layer 360 DVDs (to simplify development, devs may even use worst case scenarios for determining how much data will be streamed at any time). On the PS3 with regard to reading speed critical data, devs can even assume the availability of a harddrive for any PS3 configuration.
IMO it's really sad the inclusion of a Blu-Ray drive received so much criticism, sure it contributed to added cost (which Sony seems to pay itself, considering all the parts in the PS3 are really of excellent quality), but the long term advantages are enormous as well as early advantages like having no disc scratching whatsoever to worry about and the PS3 producting far less noise than 360s. Blu-Ray movie playback out of the box should IMO be looked at as a nice added bonus for those interested, but with regard to gaming it's also an important aspect to how the PS3 distinguishes itself with regard to long term potential compared to the 360.