Hrm, maybe. I think social/casual gaming with virtual goods are here to stay (they've been growing like crazy in asian countries for years and years). Groupon isn't particularly defensible, but the model seems to scale infinitely, and restaurants.com has been doing it with less splash for years. Groupon's 50% margins will get trimmed over time and certain types of merchants will realize that it's a pile of fail for their business... But why won't Groupon and it's ilk always be a great deal for businesses like restaurants and spas (especially if they start allowing for blackouts on weekends?).