Why I can't upgrade to vim 6.3 or above using yum on CentOS 6.0

Why I can't upgrade to vim 6.3 or above using yum on CentOS 6.0

I'm trying to upgrade to vim 6.3 so I can improve my vim skills using an
online vim book
(http://learnvimscriptthehardway.stevelosh.com/chapters/00.html). I'm
trying to update my vim package (which is currently at version 6.2.411).
why can't I upgrade ?
[foo@bar ~]# yum update vim-enhanced
Loaded plugins: fastestmirror, refresh-packagekit, security
Loading mirror speeds from cached hostfile
* base: mirror.nbrc.ac.in
* epel: mirror-fpt-telecom.fpt.net
* extras: mirror.nbrc.ac.in
* updates: mirror-fpt-telecom.fpt.net
Setting up Update Process
No Packages marked for Update
[foo@bar ~]#
[foo@bar ~]#
[foo@bar ~]#
[foo@bar ~]#
[foo@bar ~]# yum update vim
Loaded plugins: fastestmirror, refresh-packagekit, security
Loading mirror speeds from cached hostfile
* base: mirror.nbrc.ac.in
* epel: mirror-fpt-telecom.fpt.net
* extras: mirror.nbrc.ac.in
* updates: mirror-fpt-telecom.fpt.net
Setting up Update Process
No Packages marked for Update
[foo@bar ~]#
[foo@bar ~]#