The folks over at Raspberry Pi have announced the immediate release of a new version of Raspbian, based on the Debian Stretch OS. There are various small software changes as well as the big update to the underlying operating system. You can read more on raspberrypi.org here and download the new image here. Please note: it is possible to upgrade from the previous version (Jessie) but the procedure is not recommended, so you may as well start with the new image!