These are the Terminal commands I recently used (October 2013) to install Git 1.8.4.1 from source on CentOS 6.4. I ran this in a VirtualBox VM after a fresh install from the ISO.
If you are not running in a VirtualBox VM, you will need run the following first.
su
yum -y install gcc make
exit
These are the Terminal commands I recently used (Feb 2013) to install Git 1.8.1.2 from source on CentOS 6.3. I ran this in a VirtualBox VM after a fresh install from the ISO.
You mileage will vary as the yum packages are updated over time. The yum install line below should include all the dependencies, at least it did for me. Eventually yum install git will include 1.8.x but until then I hope this helps.
cd ~/Downloads
su
yum -y install zlib-devel openssl-devel cpio expat-devel gettext-devel curl-devel perl-ExtUtils-CBuilder perl-ExtUtils-MakeMaker