Reminder:

As of February 2012 Scientific Linux 4 has been receiving no updates of 
any type since it has been designated End of Life.  The extra length of 
public availability was provided for sites which have continued to run 
Scientific Linux 4.

For the last few months it has remained in the standard location.  On 
June 12 2012 we will be moving all instances of Scientific Linux 4 into 
the 'obsolete' directory under /linux/scientific/ .  This is the same 
place that Scientific Linux 3 has been since it was archived.
They will be at /linux/scientific/obsolete/<version name>.
This move will break all yum update operations that use the old path.
If you wish to use our archived copies you may update your
/etc/yum.repos.d/ files to point to this archived location they can
still function while the archive is available.

Again, this is location where we will archive Scientific Linux 4 after
June 12 2012. We have no plans to delete Scientific Linux 4 or
Scientific Linux 3 at this time.  We are merely making a clear
distinction between current distributions, which can receive updates,
and obsolete ones, which will not receive updates.

Sites requiring Scientific Linux 3 or Scientific Linux 4 should make a 
local copy of these trees so that they are always available to you if 
you need them.  You can then update your /etc/yum.repos.d/ files to
point to this local mirror for increased performance.

No modifications of Scientific Linux 5 or Scientific Linux 6 will be 
made as a part of this change.

-- 
Scientific Linux Developers