Yeah. I'm not sure the version of Blue Gene that the University ordered has it, but IBM plans to start making the Blue Gene with the Cell Brodband engine (with all 8 SPEs, the PS3 has one disabled)
the collection of PS3's your thinking of is Stanford Universities Folding@Home application. and yes it is over 1PFLOP. (hundreds of thousands of PS3s have signed up. something like 33000 active PS3s. I have my PS3 running the program right now)
and if you wanted to you can buy a cluster of PS3's, you can get them from Terra Soft (with Yellow dog linux installed) for $17500(8node) or $42000 (32node).
With the supercomputer you would get more ram, and many more processors. Like it says up there, the blue gene has over 8000 processors. and to reach 1PFLOP you would need over near 30k processors.