Doesn't seem to be available for RHEL6. Needs to be packaged separately.

itstool is available for F15, I've pinged Shaun to have it branched for EL6 as well and we should be good to go.

FYI: I grabbed the F16 version and rebuilt an EL6 package for it.

[jschroeder@clutter SPECS]$ pkgbuild6 x86_64 itstool.spec 
INFO: mock.py version 1.1.21 starting...
State Changed: init plugins
INFO: selinux enabled
State Changed: start
INFO: Start(/home/users/jschroeder/build/SRPMS/itstool-1.1.1-1.el6.src.rpm)  Config(epel-6-x86_64)
State Changed: lock buildroot
State Changed: clean
INFO: chroot (/var/lib/mock/epel-6-x86_64) unlocked and deleted
State Changed: unlock buildroot
State Changed: init
State Changed: lock buildroot
Mock Version: 1.1.21
INFO: Mock Version: 1.1.21
INFO: calling preinit hooks
INFO: enabled root cache
INFO: enabled yum cache
State Changed: cleaning yum metadata
INFO: enabled ccache
State Changed: running yum
State Changed: creating cache
State Changed: unlock buildroot
INFO: Installed packages:
State Changed: setup
State Changed: build
INFO: Done(/home/users/jschroeder/build/SRPMS/itstool-1.1.1-1.el6.src.rpm) Config(epel-6-x86_64) 1 minutes 41 seconds
INFO: Results and/or logs in: /home/users/jschroeder/build/RPMS/
State Changed: end

After a bit of yum repository mucking and puppet work...

[root@webapps ~]# rpm -qi itstool
Name        : itstool                      Relocations: (not relocatable)
Version     : 1.1.1                             Vendor: (none)
Release     : 1.el6                         Build Date: Tue 17 Apr 2012 12:38:02 PM UTC
Install Date: Tue 17 Apr 2012 12:49:10 PM UTC      Build Host: clutter.gnome.org
Group       : Development/Tools             Source RPM: itstool-1.1.1-1.el6.src.rpm
Size        : 93989                            License: GPLv3+
Signature   : (none)
URL         : http://itstool.org/
Summary     : ITS-based XML translation tool
Description :
ITS Tool allows you to translate XML documents with PO files, using rules from
the W3C Internationalization Tag Set (ITS) to determine what to translate and
how to separate it into PO file messages.