writes "Cray announced two new high end supercomputers, today: The XT4
is a very slight upgrade from the prvious XT3 supercomputer, supporting AMD's new opteron processors with DDR2 memory. The Department of Energy's Oak Ridge National Lab has announced that they will install a Petaflop system based on the XT4. Like the XT3, the XT4 supports up to 30,000 processors, and uses the same microkernel operating system on the compute nodes, and Linux on the I/O processors. The XMT
uses the same cabinets, interconnect, I/O nodes, and system boards as the XT4, but uses Cray's custom multithreaded processors. The XMT makes use of the AMD Torrenza platform to put custom processors into opteron sockets. The XMT is the next generation of the MTA platform, dating back to the origonal Terra Corporation. More coverage at CNet."