Robert_Charlton - 10:04 pm on Sep 30, 2010 (gmt 0)
Note that the Place Pages have had a free link section for quite some time now: Nearby places you might like
The nearby places aren't ads but are algorithmically determined free links, and it could be argued that they're more threatening than the ads, because, from what I've seen so far, they're for nearby competitors and they're a lot more relevant than the ads are. I think the ads have been around for a while.
These pages are prone to hijacking and external edits unless the owner "claims" them. I recently reported the hijacking of a page of a place I patronize (someone changed the url of the website), and it was fixed quickly.
Review content is subject to abuse everywhere. You can flag the Google reviews as inappropriate, which is a better break than many review sites give you.