It’s a nice idea but I see a few problems with it.
- SpamReporter itself open to spamming. If the spammers start spamming SpamReporter with a bunch of legitimate blogs, the information in it will be useless. Maybe using a Captcha or something would help.
- I’m not sure I see how the blog search engines could use this data. Just because a blog is marked as spam by someone doesn’t mean it is really spam. Maybe the more “spam votes” a blog gets would reduce it’s relevancy or something, but I’m just not sure how much sense that makes.
- If this data is publicly available, the spammers will be able to use it too. As soon as they find out one of their spam blogs is on the SpamReporter list, they just start up a new free blog.
I hate to criticize a well-meaning project, but hopefully my suggestions can make it a better service.