I'd like to know this too. I keep a scrapbooking blog with blogger and I always just delete the one's that are in the spam box. Every now and then thought I'll have some in the comment moderation section that leave links and I delete them. I have that comment moderation on my blog so that I see them and have to approve before going on my blog. I'm not sure if this helps with the spammers or not, but I hope it does.
