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]
This is currently a known source of spam, and one of the reasons why in many countries all Map Maker edits must be approved by at least one trusted reviewer before they are being published. Unfortunately the edits you found passed that review without being detected.
There are several methods to report this type of spam. One is what you have already done by reviewing the edit and marking it as spam there.
Another method is to open the profile of the mapper. That profile should be accessible through a link which is available within the edit. If you open that page, you will see a "Report user as spammer" link in the upper left corner.
If this type of spam is happening a lot in your area with different spammers, it is not a bad idea to also inform the reviewers who are active in that area to watch out more. You can do that by finding the Map Maker Advocate who is active in that country or state through http://sites.google.com/site/mapyourworldcommunity/advocates [sites.google.com] and send a message through their Google+ account. They should be able to inform the reviewers who are commonly reviewing in that specific area.