Scientific Linux 5.6

Scientific Linux is a Linux release put together by Fermilab, CERN, and various other labs and universities around the world. Its primary purpose is to reduce duplicated effort of the labs, and to have a common install base for the various experimenters.
This is new variant of linux, their goal for base distribution to have everything with enterprise.
You can get more information from official website of Scienfic Linux here
also you can download from that site