Barry Abrahamson, working for Automattic, reveals some technical details about the new data center located in Chicago. This is one of the three data centers that work WordPress.com. The iron that is installed in it:
150 HP DL165 servers with dual-core AMD 2354 and 2-4 GB of RAM
50 HP DL365 servers with dual-core AMD 2218 and 4-16 GB of RAM
5 HP DL185 servers with two quad-core AMD 2354 and 4 GB of RAM
In total, this is 1440 cores and something between 520 GB and 1.4 TB of RAM.