Scientific Linux release 4.8 is based on the rebuilding of RPMs out of SRPMs from Enterprise 4, including Update 8. It also has all errata and bug fixes up until July 20, 2009.

About Scientific Linux
Scientific Linux (SL) is a Linux distribution produced by Fermi National Accelerator Laboratory and the European Organization for Nuclear Research (CERN). It is a free and open source operating system based on Red Hat Enterprise Linux and aims to be 100% compatible with and based on Red Hat Enterprise Linux.