Past, Current and Future
Google and many other search engines such as Yahoo and Bing are already factoring in social media interactions. Such as Tweets, Likes, Shares, Pintrest, Google +1, Reddits and so on. This have been using social media in their algorithms for some years now and they are constantly updating it.
Using Social Media is a Ranking Factor
It is advisable for any site... business or personal to have social media platforms integrations as they do contribute to rankings as well as gaining visitors from these networks which ultimately can spread the word by also using social media or by back linking directly on a blog of some sort.
You heard of things going viral? Well normally this happens on social networking first.... not always but most of the time and Google rewards for this hence they monitor social media. So yes... It's advisable to use social media BIG TIME ;)
SEO Profilers can tell you what your online presence is like
Check out a woorank.com which is one of many that can tell you and your competitors social likes and so on.
Or are you refering to actual FACEBOOK crawling? what people link on their walls without visiting a website and clicking the share/like button?
PS. What blog did you read? Either a outdated one or a future one perhaps which they may factor it in even more into the rankings.. Let us know if you find it.