How many times must I point out Uncharted and Ratchet & Clank. >_<
It's all in the way you use the disc. Many ps3 exclusives are often barely compressing data on the disc (some things aren't compressed at all) so that they can then be streamed directly from the disc during gameplay, resulting in no installs nor loadtimes like Uncharted, or no installs with little loading like Ratchet & Clank.
Multiplats, for the most part, are made with the 360 in mind, so instead of utilizing drastically different methods of loading data off the disc for each version, they use more traditional methods for both consoles while throwing in the HDD to assist the ps3's Blu-Ray drive.
If the added space of Blu-Ray is effetively used, you can end up with a game like Uncharted. Stunning graphics, high rez textures, no installs, no loading, etc.
