I had a comment recently which was basically saying that they were getting triple emails for each comment received on my blog and they asked if I could sort this out for them. I haven’t approved it as I am slightly worried it might be spam (although it didn’t read like spam at all… )
anyway, the upshot is, I can’t seem to do anything about comment subscription – I can’t even see *who* has subscribed to comments, just how many. If you want to unsubscribe from comments, it looks as though there should be a ‘modify your subscription options’ in the emails you receive. There is also this help page on wordpress.com http://en.support.wordpress.com/following-comments/
hopefully that helps….