The do have legitimate competition abroad and they just purchased Accoleo to get a physical presence in Europe.

Additionally, expansion in the U.S. is going to come at a higher cost as they battle for the lucrative vacation rental market with other well-funded companies like VRBO.

Airbnb is really interesting because their relatively agnostic platform can hit a huge market - couches, single rooms, apartments, houses, boats, independent hotels, etc., along with a lot of international markets to play in, whereas competition has generally been more focused on satisfying a specific segment.

I'll be very curious to see how this company's next series of strategic decisions play out, given this very nice Series B.