I'm going to let self-promotional comments through for a while. Not comment spam, mind you, but if you take the time to personalize a comment rather than submitting it via a machine, I think having self-promotional comments wouldn't hurt, as long as they're not submitted en masse. Had to think about this a bit when someone wrote a response to my Why (Free) Online Poker Sucks post. The post did link back to a poker site, but it was well-written and actually contributed something to the dialogue. Comment spam doesn't do that.
If I'm inundated, I reserve the right to change the policy.