5m guest reservations have been made on Airbnb

"Airbnb, the online marketplace where you can rent out your house or spare room to travelers, announced today it has reached a milestone of five million guest reservations overall. The company also celebrated its strong international growth, with property listings in more than 19,000 cities in 192 countries around the world.
In terms of reservations alone, 2011 was a great year for Airbnb. The company launched in 2008 and it took about three years to reach one million bookings. In the last year alone, more than four million reservations were made, bringing Airbnb’s total to a cool five million.
The company also brought in some serious funding in 2011. Last July, investors gave Airbnb $112 million at $1.3 billion valuation, bringing the company’s total funding to $119 million dollars.
[...]

The online listing and booking service is paying off for many in a big way; earlier this week we reported that New Yorkers are making an average of $21,000 per year by renting out their spaces to travelers. The legality of renting out spaces for short periods of time is questionable in some cities, but people have flocked to the service none the less."

Source:  VentureBeat, 26th January 2012