Last week I discovered Google Map Maker after I read about it in a Google announcement that was discussed here.
I've been playing around there. I added some missing roads, and corrected some inaccurate info about local business. Then I started reviewing edits that other people made. It didn't take me long to find SEO spammers.
Here is how it seems to work:
Spammer looks around for business without a website listed in Google Local.
They edit the business with Google Map Maker to add a url.
This spammer was using a format like http://businessname.example.com/ that would redirect to the spam website.
The spammer has a list of competitors with ads on that website.
Even before the change is approved in Map Maker, businessname.example.com starts showing up number #1 above the organic listings when you search for the business name on Google search.
As part of my review, I reported this particular abuse as spam. I'm not sure how one would go about finding other examples from the same spammer that have already been approved. If you did find other examples, I'm not sure exactly how you would report them.
In any case, if you depend on local SEO, keep an eye on your business listing and make sure your website is up to date with your official url.
[edited by: tedster at 1:40 am (utc) on Aug 28, 2012] [edit reason] make example URL display in full [/edit]