The following errata for CentOS-2 have been built and uploaded to the centos mirror:

RHSA-2008:0134-01 Moderate: tcltk security update

Files available:
expect-5.38.0-75.i386.rpm
itcl-3.2-75.i386.rpm
tcl-8.3.3-75.i386.rpm
tcllib-1.0-75.i386.rpm
tclx-8.3-75.i386.rpm
tix-8.2.0b1-75.i386.rpm
tk-8.3.3-75.i386.rpm

More details are available from the RedHat web site at
https://rhn.redhat.com/errata/rh21as-errata.html

The easy way to make sure you are up to date with all the latest patches is to run:
# yum update