The rule for social media inclusion in SERP ranking is the same as any other link on the internet: someone links to you from these places, you get link juice. But there are a few things to be aware of.
Facebook employs privacy options for every user profile (not pages). What this means is that any individual user can either leave their profile completely open to the world, or put an absolute lock-down on anyone except their friends. If a user makes it to where their profile is private, Google cannot crawl their profile. It's sort of like employing the robots.txt to block Google. Therefore, the only way you can get any
juice for your link profile from Facebook is if the user linking to you has their space on the web completely open.
Twitter employs rel="nofollow" in all outbound links from the site. This basically means that any link pointing from www.twitter.com
to any other place on the web does not ad PR
and assist in raw ranking on search engines. However, if you'll refer to a thread that Deepsand and Myself have been involved in for a few days now, you can get an understanding of how rel="nofollow" attributed links can
Here is the thread:
No difference between No follow & Do follow?
Catch up to the posts by Deepsand and you can get an especially nice explanation about the difference between the two existing "nofollow" options. I also make some points on this subject that may be worth reading.
Now remember, these are only two
social networks out of the hundreds or thousands that exist. We may never know all of the rules for all social media platforms, but what we can do is bring our reputation to higher levels so our loyal fans become our own little army of advertisers. Gotta love the webmaster / web-viewer bond!
Hope this helps!