Zen subtheme: no sidebar on a given page
After some tests which involved using arguments in page.tpl and CSS trickery to clean up after, I couldn't manage to have a proper working solution.

Although I would have prefered to find a way to do this at a template level, easiest and quickest solution I finally found, was to use Context module 

Basically I created a simple context with a Condition on path option and a Reaction on regions of the concerned theme. Checked the sidebar I wanted to exclude Saved and it was done. 

Good thing doing this through the Context module is that, it removed the concerned regions, but most importantly it removed also the corresponding classes from &lt;body&gt; which were the pain in the butt to begin with.