People are asking me all the time if Social network Links help SEO. Well Do they?
Here is brief video (Under 3 mins) of Matt Cutts (the face of google Search/Spam team)
Basically if you are not spamming the engines and you have a good reputation in Social it will have some affect.
Thanks. At least I am not wasting my time here on FB and Twitter!!
As long as you are adding value and maintain a real profile (not bot run) you will gain something.
I also heard it mentioned, but unverified that if you get 2 retweets of an original tweet you gain some seo benefit, even if it is a bit.ly URL.