ExaFLOPS in 2012

Sandia and Oak Ridge recently received a 7.4 M$ grant to "conduct the basic research required to create a computer capable of performing a million trillion calculations per second, otherwise known as an exaflop" (link).
"In this amazing and expanding universe !" I'm tempted to add to that millions trillions, but what I'm even more tempted to do is a back-of-the-envelope calculation of a folding@home-style distributed computing project using 8th-generation gaming consoles ("PS4s").
For a nicely parallel algorithm you can currently milk around 67 GFLOPS from a PS3 under Linux using minimal contortion. If you could access the RSX GPU (which is locked under Linux) , that figure would probably increase about fourfold.
Historically, peak console CPU+GPU computing power increased roughly 60-fold in the 4.3 years between the release of the PS1 and the PS2, and a further roughly 100-fold (the exact architecture of the RSX is unknown) in the 7.7 years to the release of the PS3. That combines to an average doubling time for peak performance of a little less than a year, somewhat faster than the 18-months doubling time for real performance commonly associated with Moore's law (which, strictly speaking, is about transistor counts per die.)
There is currently some speculation about the next generation of consoles being released a few years earlier than the 6-year-cycle we've seen so far. Let's just pull a release date of mid-2011 out of thin air, and "Moore's law" points to a tenfold increase in real computing power, which looks flimsy compared to the above figures. So if we extrapolate the past trend for peak power, and assume we can use the new architecture as efficiently as the current one, we get a more handsome 40-fold increase, which translates to roughly 10 TFLOPS per console.
So you would need 100.000 consoles running simultaneously to break the exaFLOPS barrier. That figure is somewhat smaller than the total number of folding@home clients installed as of 2008, but larger than the number of PS3 clients for that project. And this figure assumes the client is running 100% of the time, which for a gaming console is unlikely to be true. (Running a 150W console 24/7 cost you about 80$ in electricity per year, depending on where you live; other factors are noise, and computing resources used for things like gaming. ) But if an organization can find a cool project and has the necessary PR skills, it should be possible to lay hands on that many clients within one or two years after hardware release. All in all this makes it look possible to do computations at more than one exaFLOPS before the end of 2012, six years earlier than the 2018 horizon for a Sandia / Oak Ridge mainframe.