It is worth noting that Argonne's IBM Blue Gene system is officially the fastest supercomputer worldwide for open science, according to the June 2008 Top 500 rankings. It is also third fastest overall, after systems at LANL and LLNL used for nuclear weapons work. Many kudos to Ray Bair, Pete Beckman, and the rest of the team at the Argonne Leadership Computing Facility. (And to IBM too ...)
Some of my colleagues, notably Ioan Raicu, Zhao Zhang, and Mike Wilde, have been running large "many task" applications in biology and economics on this system, using Falkon and Swift. So far we're up to 32K of the total 160K cores, and it's a delight to work with.