With Google starting to look at social media signals to help shape their ranking algorithm (though to what extent we're not yet sure) it would seem that the future of the paid link is already in place.
Following on from reading this article on SEOBook about Social Spam, it got me thinking that if Google are to use likes/plus ones/retweets as a ranking factor, how are they going to deal with things such as this:
There's already plenty of "RT to win" promotions going down on Twitter, but I would imagine the argument for those is that you don't necessarily get anything in return for your sharing of the link - whereas with the above - you get $5 credited to your account, the steps are as follows:
1 - Log into to both your Twitter and Amazon accounts.
2 - Automatically follow @amazonvideo. The message “I just got a $5 credit for instant movies and TV shows @amazonvideo. Click http://amzn.to/hh8gTP to get yours. #get5″ will be automatically tweeted from your Twitter account.
To me, this is different to the out and out social media spam that you can buy which will guarantee you followers & retweets or fans & likes - those sort of accounts are presumably easier for Google to spot as most often have a high number of followers and a low number of tweets etc.
So the question for me is - how will they determine promotion from paid tweets and in turn from spam?
As an aside, I do hope any tweet containing a link and "Can I get a RT" which is sent to any celebrity is punished with a Google Penalty - that'll learn 'em.