In a response to a question on Twitter concerning purchasing games from a smartphone, Sony Worldwide Studio boss, Shuhei Yoshida, stated that when you purchase a game using your smartphone, the PlayStation 4 will wake itself up and start downloading it.
The tweet stated, "When you buy a PS4 game on smartphone, it will wake your PS4 to start downloading the game. PS4 goes back to sleep after that.
In an earlier interview with Eurogamer, Yoshido stated that, "You can play offline, but you may want to keep it connected," he suggested. "The system has the low-power mode - I don't know the official term - that the main system is shut down but the subsystem is awake. Downloading or updating or you can wake it up using either the tablet, smartphone or PS Vita."
The PlayStation 4 is scheduled for release on November 15th of this year in North America and on November 29th in Europe, New Zealand and Australia.