I'm having the same problem as Valent Turkovic. I have the following /etc/yum.repos.d/CentOS-Base.repo (mind the line-wraps):
[base] name=CentOS-$releasever - Base mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch= $basearch&repo=os #baseurl=http://mirror.centos.org/centos/$releasever/os/$basearch/ gpgcheck=1 gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
#released updates [updates] name=CentOS-$releasever - Updates #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch= $basearch&repo=updates baseurl=http://mirror.centos.org/centos/$releasever/updates/$basearch/ gpgcheck=1 gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
#packages used/produced in the build but not released [addons] name=CentOS-$releasever - Addons mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch= $basearch&repo=addons #baseurl=http://mirror.centos.org/centos/$releasever/addons/$basearch/ gpgcheck=1 gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
#additional packages that may be useful [extras] name=CentOS-$releasever - Extras mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch= $basearch&repo=extras #baseurl=http://mirror.centos.org/centos/$releasever/extras/$basearch/ gpgcheck=1 gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
#additional packages that extend functionality of existing packages [centosplus] name=CentOS-$releasever - Plus mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch= $basearch&repo=centosplus #baseurl=http://mirror.centos.org/centos/$releasever/centosplus/$basearch/ gpgcheck=1 enabled=1 gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
I have missed any fixes for this since the suggestion to comment the mirrorlist line and uncomment the baseurl line (which doesn't work.
Thanks in advance.
-- Bob Taylor