When using Ubuntu 11.10 on my workstation to build core-image-sato for the meta-cedartrail under meta-intel, I had to add the XML::Parser for perl package. I was getting the error XML::Parser perl needed to run initool.

the command to install the missing package is:

 sudo apt-get install libxml-parser-perl

I'm not sure at what distribution level this became a requirement, but at least for Ubuntu 11.10 it is required. 

This package should be added to the Quick Start Guide under "The Packages" section