C'mon people. Look at all its doing in the background and really think about it.
Playing game in foreground. (utilizing nearly all CPU and GPU)
background using 2nd processor....
HD Video streaming (game)
Audio streaming (game)
Video streaming (friend)
Audio streaming (friend)
HD Video recording
text/sms based messaging
downloading / content management
This is equivalent to running:
Battlefield 3 in an online match while video skyping with a friend AND having google up in the background refreshing chat and emails etc AND running your torrent downloads on a PC.
Yes it will all be more optimized to the hardware than Windows is, but it still requires a lot of ram for states, buffering, etc. Even WiiU which does almost none of that simultaneously with a running game, uses 1GB. PS4 will be doing all of that while the game is fully running and loaded.
This is why I changed it from .5 to 1GB for OS to 1GB+ for OS. Its going use a lot of RAM.