Here is a great way to keep your subversion up to date using Yum.

First check what you are dealing with:

yum info subversion

yum info mod_dav_svn

The 32 bit version seems to cause issues on Updates so delete:

yum erase subversion.i386

Edit the CentOS repo to exclude protecting subversion and mod_dav_svn

nano /etc/yum.repos.d/CentOS-Base.repo

Add to [base] and [update]

[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=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5
priority=1
exclude=subversion mod_dav_svn

#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=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5
priority=1
exclude=subversion mod_dav_svn

Do the actual update commands for the apps... do subversion last:

yum update mod_dav_svn

yum update subversion

Check to see if the update was succesful:

yum info subversion