While I don't think Groupon is sustainable as the darling of both consumers and the businesses who use it to sell, one aspect of the deal that makes sense to me

While I don't think Groupon is sustainable as the darling of both consumers and the businesses who use it to sell, one aspect of the deal that makes sense to me is that it makes Google a viable first destination when someone is wanting to purchase a product (when they integrate Groupon in searches). When purchasing intent is there, Google makes significant revenue on searches. As Eric Ries has broken down, as long as the e-commerce world is sufficiently fragmented, users will prefer an intermediary like Google to help them find the right product or merchant. This deal, if it went through, is a step by Google in keeping e-commerce fragmented.