Glenn Gabe just pinged me that he is now seeing Groupon showing up in Google Place SERPs:
According to Glen, this sucks for Groupon advertisers because:
All of the Groupons I came across were expired. That’s right, when you click through the link in the clustered results, you end up at the Groupon page for the business (with the expired discount staring you in the face.) Imagine a customer searching for a spa treatment, finding your Groupon page (where you provided a huge discount), then finding out they can’t get that discount, and then possibly taking measures based on that fact.
Read the full analysis here.