I've noticed that when verifying Google+ authorship on Google's Structured Data Testing Tool for various sites that only the www OR non-www version of a page will show verified authorship - not both. This, obviously, depends on which link is connected from the author's Google+ profile. Matt Cutt's site, for example, is only verified on the www version.
Does this mean that we should be verifying Google+ authorship to both www.mydomain.com as well as domain.com to give ourselves the greatest chance of having our nice little photo show up in the SERPs? Or, if our pages are properly tagged, will only the canonical version of the page be served in the search results (so we only have to G+ verify the canonical page)?