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.

Watch Dogs has been announced as a PS4 launch game, and the other versions of that game are coming out November 20th.

http://www.computerandvideogames.com/392534/watch-dogs-confirmed-for-ps4-launch-new-gameplay-video/

The PS4 is coming out November/December

The earlier they launch the better right? If they launch in November, they'll be damaging the performance of cross-gen games.

There doesn't seem to be anything stopping them, so you might be right.

Just to be clear I said the console is ready to launch even in October if Sony wants but Sony that make the launch... so who knows when Sony will launch it.

The official approval for the launch is already done... so now Sony needs to give us a DATE... gamescom is ready for that

Youll know before it happens.

I will predict two dates for November...

November 1, 2013
November 8, 2013

And one date for October...

October 25, 2013

I think Nov 1 is really a great date.

As far as I know, those holidays don't even exist in all (probably most) countries they plan to launch in, and I'm under the impression they were talking pretty internationally.

What mean "Holiday" in US? Oct-Dec?

I have thought this the whole time. Sony is on top of things this time around, and is going to have heaps of stock for this holiday. I think they want to get out ahead of XBO and try to steal as much buzz as possible. My guess right now is PS4 will be on shelves no later than the last week of October.

How about "Talk like a pirate day" - November 19th? 

In all seriousness, I think early/mid November is likely.  November 27th is a popular pick from analysts for when XBox One will release.  My prediction is that Sony will try to beat XBox One to market by at least 1 week, both for competition's sake and to avoid inevitable retail hell.

Can you imagine a combined launch date?  Rows of tents in front of electronics stores with face to face fanboy wars ensuing.  It would be chaos.