For those still also with one of the big listing sites, you have told us that they will penalise you if you take bookings on your own site, both with charges and by lowering your listing.
According to consensus, the safest way (currently) is simply to block the dates off. This way the OTAs do not know that you have taken a booking as you do not have to put in any details about who is staying.
The Soup will also start including calendars, probably later this year. We have deliberately held back on this so far until we have sufficient density of properties, as it encourages more people to go to your site. When we do include calendars we will obviously use iCal. Having one calendar that runs everything should be everyone’s goal, and you must own that calendar (not VRBO for instance), which means it probably must be iCal.
When we start preparing you for Calendar integration, we will give you more information on the ways you can do so, we wanted you to know the direction we are going in so that you can prepare, and not lose out from the listing site’s attempts to control you.