VentureBeat reports that Pinterest has notified their top contributors that they are automatically removing any affiliate links, redirects and tracking scripts from their posts.
Here is the statement Pinterest gave VentureBeat:
We are removing affiliate links to ensure we’re providing the best possible experience for Pinners. Recently, we observed affiliate links and redirects causing irrelevant Pins in feeds, broken links and other spammy behavior. We believe this change will enable us to keep the high bar of relevancy and quality Pinners expect from Pinterest.
The thing is, the top contributors to Pinterest were mostly contributing because they were able to monetize it through affiliate networks. Pinterest just killed that and it will be interesting to see how these top Pinners react.
Back in March 2012, Pinterest added nofollow to their external links after SEOs started taking notice to the social network.
Forum discussion at WebmasterWorld.