This is still listed as a feature of the Availability setting:
"Buyers will not be able to place a new order when you are marked as out of the office."
Sorry if this has been addressed previously, but one thing that I personally would find REALLY useful would be the option to set Out Of Office mode, yet STILL be able to send out Custom Offers for existing clients, or potential clients you are in talks with via the messaging system. Say, for example, if you're busy on long projects outside of Fiverr (or even on Fiverr), but would still be able to do certain shorter jobs while the OOO mode is set.