From the original article: "In the biggest study of its kind, we have found that there is strong correlation between the amount of tweets about a URL, and its Google ranking.
1) Study shows that URLs receive a significant boost in Google rankings when they are shared on Twitter
2) The effects of this boost seem to level out at around 50 tweets, and the subsequent benefit of gaining additional tweets is minimal until around 5,000 tweets
3) After 5,000 tweets the average ranking of URLs improves considerably
URLs receiving over 7,500 tweets almost always rank inside the top 5 results
4) Average rankings are heavily correlated to the number of tweets about each URL".
You better read it. 8/10
Full article: http://www.branded3.com/tweets-vs-rankings
Via Antonino Militello, Robin Good