From the +Mashable article:

The bottom line is, the SEO effects of a +1 are very indirect, which means traditional SEO practices should not be ignored. SEO methods such as link building, relevant keywords, and URL structure have a more significant impact on page ranking.

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How Google's +1 Button Affects SEO
Google's +1 button doesn't share content to the stream the way the Facebook "Like" does, but there must be a connection to search. Here's what we know so far.

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