Mike Blumenthal has been covering Google Maps spam since Google Maps came out. I guess he got sick of covering the issues and not much being done about stopping it. He decided to do something a bit extreme. He hijacked Microsoft's listing in Google Maps and made them a Microsoft Escort Service. He also messed around with profiles, here is one example:
Danny Sullivan has a really enjoyable read on how Mike did this.
While some SEOs and webmasters are shocked this can happen, those of us who have been around and watching the space has known this has been going on for a while now. Who is to blame? Businesses should validate and acquire their Google Maps listings? Do they even know they are able to do so? Are they aware? Is ignorance an excuse?
Meanwhile, Maps Guide Brian, an official Google Maps representative posted a Google Groups thread stating that they will be upgrading the Local Business Center:
Please note that that the Local Business Center will be undergoing scheduled maintenance today, October 30th, and again on November 6th. We appreciate your patience as we work to continue to improve this product!
Hopefully this upgrade or maintenance will help prevent some of these issues. I know Google is a big target and the more features and tools they release, the more susceptible they become to becoming targeted. It is a tough business and sometimes it can be hurtful. You build tools to help people (of course also make money) and people come in and abuse it.