Google has the Google Local Business Center where you can add or edit your business listing in the Google Local results. I wrote about the edit business listing process before as well as wrote a really long one on How To Add Your Local Business Ad In Google AdWords while at Search Engine Watch (but none of the images work now - not to SEW, please fix the broken urls).
But now it appears that some devious businesses are registering their competitors businesses with Google local, but placing their URL in the business listing. Gabs also blogged this... A DigitalPoint Forums thread has one such report where the individual said:
I have a client, who did not register a business listing on Google maps, but their competitor took the time to do it for them, using their own url instead of my clients of course.
The listing shows as unverified, but I imagine that could stay that way for months.
You might want to check your Google map business listing to make sure someone hasn't done the same to you.
Google recently made the local Google results larger in Google.com normal searches, so this is more important than ever.
In addition you can update the listing and verify yourself as the true business.
Forum discussion at DigitalPoint Forums.