Dave – great post. But I think there are a few more things to be considered… Re: #3 – I think you’re missing a big part of the equation. You’re looking at the P&L but only focusing on the L. If you start making money on each new business that signs up, then you don’t need to take a huge investment to grow the market. Look at Groupon. 18 months old and already generating tons of cash…. and each new business they sign up is hugely profitable. I actually think Groupon is a much bigger threat to Foursquare than any of the ‘Big Tech’ companies you mentioned. Ultimately, both are building CRM for small local businesses. Foursquare is coming at it from the ‘Loyalty’ perspective and Groupon is coming at it from the ‘Utilization Management’ perspective (bookings are a little low for Monday night? Why not blast out a real-time Monday Night only deal to get butts on seats).