Dr. Pete over at SEOmoz just posted a good one shedding some light on an important but often confusing topic that can deals with your on-site SEO and therefore can impact your Local SEO results.

Rel=Confused? Answers to Your Rel=Canonical Questions | SEOmoz

Itís been over four years (February 2009) since Google and Yahoo announced support for the rel=canonical tag, and yet this single line of HTML is still causing a lot of confusion for SEOs and webmasters. Recently, Google posted 5 common mistakes with rel=canonical Ė itís a good post and a welcome bit of transparency, but it doesnít address a lot of the questions we see daily here in Q&A. So, I thought it was a good time to tackle some of your most common questions...