Ok, it's long over due to have a real calendar. I have been providing this feedback for many years.
For example if I get a renter for next monday and tuesday night and I block out my calendar on airbnb for monday and tuesday those two days are completely shaded off. What should happen is the second half of monday should be shadded, all of tuesday and the first half of wednesday since those are really the times when the place isn't available. Thus if I quickly glance at the calendar I can see when people arrive and leave and can answer questions correctly for inquiring guests.
Not as important, however if airbnb wants to play a big role and be a real player....make themselves more sticky in our businesses, they should enable us to enter in rental amounts for days we block off that we have personally rented. Having a real system with a real calendar that tracks what is truly used or open, along with tracking the money being recieved would be customers will always see the most accurate availabilty and hosts will make fewer mistakes, want to use the airbnb calender and thier calendar of record and do thier book keeping within airbnb instead of needing to track things outside the system.