[Updated] World's most powerful Linux supercomputer by IBM, will use AMD Opteron CPUs which is definitely a vote of confidence for AMD. (especially considering IBM chose the Opteron over their own Power 4 CPU!) It's set to be the world's 3rd most powerful supercomputer "system will comprise 1058 dual-processor 1U rack-mounted eServer 325s. Each server is based on a pair of AMD Opteron 200-series CPUs, including the Opteron 246 (2ghz), IBM said."

Opteron's are going to be used in other super computers too. Apparently they scale much better than dual Xeons do. Adding a second Opteron get's you nearly twice the speed, whereas adding an extra Xeon gets you 1.09x the speed.