Sorry! I am not understanding how a Re Tweet helps with any lift in rankings.

[SEObleu.com]

Does anyone have an infographic to explain how social media increases any lift in the SERP's.  I just am not grasping how if I re tweet a link that the search enegines see this and say "this must be important" let rank it higher..

Where is the Social Media Moz Guru?

[MarieHaynes]

This article will likely help you:

http://www.seomoz.org/blog/google-bing-confirm-twitter-facebook-influence-seo

A single retweet is not likely to make a big difference.  However, if someone influential retweeted you (i.e. like Rand) then this is a signal to the search engines that your post is significant.  The article describes how the tweets from someone of authority are important.  Similarly, if your article gets tweeted for facebook-shared in multiple circles around the world this is a sign to the search engines that it is an interesting article and worth looking at.

Tweets and shares are not the new links, IMHO, but if you write something that's good enough to get valid, genuine attention from others then Tweeting and Sharing are indicators to the search engines that your article is a good one.  So really, it comes down to producing great stuff.

[Nextman]

Hey there. I think that the main benefit from Twitter, or one of them, is if when you post a link to your own site, like your blog, for a start you use a shortner like Bitly. If the link becomes very popular and is retweeted by many, it gets listed on various sites which list 'hot stories'. This gives you quality followed backlinks on high page rank sites. Also, the use of bitly to shorten the link allows a super popular link to be stored and give you a really powerful back link from the Bitly site.

Also the retweets within themselves are classed as social signals and are taken into account by search engines, but it is a viral and very popular tweet sent promoting a a url on your own website that gives the most benefit.

Right now our strongest back link is from a blog post that was retweeted over 500 times. The main backlink just shows as a bitly link, with the domain stats of the bitly website.

Hope that helps.