A new category of x86 servers has appeared on the market recently: ultra high density servers. Companies such as Rackable,IBM, Dell and probably others are shipping these systems now.
These are designed to provide more than the usual 42 server maximum per rack, have lower power requirements and by using COTS components are usually less expensive than similar more proprietary devices.
I'm interested in discussing your experiences with these servers. How you're using them? How many do you have? Who made the servers you have? What issues have you had with them?