I agree with the above but on the other hand, if I was searching for places to stay in a city and found out that an old friend of mine was on Airbnb for that city, I would jump at the chance. I haven't used Airbnb but I would really push an initiative to feature friends on the site via FB connect.
Friends don't generally charge each other money to stay at their place though, right?
Or maybe that's a difference between close friends and acquaintances--and many people have a lot of acquaintances for Facebook friends, so I can see it working out.
Maybe not a 1st degree friend but a friend of a friend or something like this.
A feature that finds out the "shortest chain" friend that rents out an apartment in your destination city would be interesting. But you need a social graph for that.
