Check out this screenie from the bottom my most recent post:
WordPress inserted that “Possibly Related Posts” stuff without me being aware of it. Hmm. If I wanted to advertise other people’s posts I’d charge for it. I think. What’s going on?
UPDATE: It’s a collaboration between WordPress and Sphere. Key point for me:
It’s setup for all WordPress.com blogs (hosted by WordPress) by default and can be turned off but if you turn it off, you won’t be included in the overall index and will lose any traffic that might come your way.