At E3 2013 and ever since, Jack Tretton and company have said that the PS4 will be launching "Holiday 2013".
VGChartz user ethomaz stated in this thread regarding the FCC approval of PS4:
"What that mean? The PS4 final version (not the devkit) is ready to launch in October or even early... a GAFer said that PS3 passed in FCC in September 15, 2006, so the PS4 is two months ahead."
'Ol Jack usually seems to have a nice smirk on his face whenever he says "Holiday 2013", probably mostly due to the fact that he knows he's skating around the "Does the PS4 have a release date?" question, but maybe they're leaving the door open to releasing around another holiday outside of what we would typically associate with "holiday" -- Thanksgiving and Christmas.
My guess is the day after Columbus Day -- October 15th.
Seriously though, I think they're being vague because they have some flexibility. Sony really seems to have their shit together this time around and it wouldn't surprise me if they release as early as October.
Note: I'm not really serious on this, more just find the idea funny. I don think the PS4 will release earlier than Thanksgiving, but as mild sarcasm can often be lost on the web, there's your disclaimer before flipping out, internet.
