The last two comments I received (on this post) were quite odd. Somebody has left a comment saying something like "Thanks! Good to see an update" and then a link to some random page advertising some stuff that had absolutely nothing to do with the content of the original post.
I decided to let the first instance go, although I was a bit annoyed. This morning I found a second comment by the same person, and so I took action and deleted both. I have also sent the guy an email to explain that I don't think this is cool, but I doubt he'll ever actually read it (or care).