Interesting topic, but the discussion could have been a lot more in depth, I thought. If anything, Grouper seems like a relatively complicated product relative to the many "feature" products out there these days - from Gantt Charts to Underwear Subscriptions...
Great article. It seems that the ends of the spectrum are what are working. Either you curate heavily like GroupOn, Fab, Fancy, etc. or sell anything like Amazon, Ebay, Craigslist, etc. Is there anyone in the middle?