RPM Fusion, the popular third-party repository for non-free packages and other out-of-tree RPMs that was a merger of Livna, FreshRPMs, and Dribble, now supports Steam. RPM Fusion supports Fedora 17, 18, 19, and Rawhide. On the RHEL side, Red Hat Enterprise Linux 5 and 6 are supported along with the EL derivatives like Scientific and CentOS. Thanks to community work, Steam can now be found for an easy RPM installation on these Linux operating systems.
For more details on fetching Steam from RPM Fusion, see this blog post for instructions or visit RPMFusion.org.