There is a FREE silo building plugin for WP put out by Network Empire. YOu can download for free from their website here: Network Empire |
Siloing is the NOW of site structure which will help you with the Hummingbird Update and the Semantic Web. It also cuts down on the number of backlinks needed.
To better understand how important it is, these are two videos from Bruce Clay who started to design and speak on it after watching Google purchase several companies just for their programs.
http://youtu.be/ue5e7fpuflU
http://youtu.be/cs92eGH9RmA