According to Maximus over at the Blu Ray forums:

Like I said it is manufacturing issues. I had it confirmed today.

The problem arose when SCE mandated SDK 350 on all games releasing after after October, GT5 was about to go gold running on SDK 341, but it has been delayed by around a week so that they can update to SDK 350. This has caused a big headache for the manufacturing side, given how big this game is missing the gold date by even a week can cause a months worth of delay as slots are already taken up at this time of year for Blu-ray movies and such. So Sony had to find a 3 week slot big enough to make 7m copies of this and get them shipped out.

If you want to blame anyone, I would direct it at the pirates and hackers, SCE never had any real SDK restrictions before firmware 3.41 was compromised.

Let this be a lesson to you all, while homebrew can be a great thing, when it messes with game releases – it’s not cool.

[Source : Blu Ray Forums]

The source that found that source out

http://www.thebrokegamer.com/2010/10/14/gran-turismo-5-delay-due-to-recent-xmb-os-hijinx/

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Nothings confirmed but a guy on the blu-ray forums says that! lol

Now what are everyones thoughts on this? It is likely to be true

And I don't think SONY plans to just make 1 SHIPMENT of the game for its entire life.....I hope 10 Million is possible.

Jesus christ thats a lot of copies

i dont really follow some of this, is this guy saying that the delay may go into 2011, i think its acceptable that they may need another week or 2 to finish up, but months....

i can't imagine they need 7 million copies at launch.  that seems like a good way to get GT to hit the bargin bin a few days after launch if you ask me...(and yes i know that you were't asking me but at this point you read it so i win regardless xD).

(if it's true)SCE think GT5 can sell 7m in December or what

ITs a new strategy perhaps.

Tekken 6 shipped 3 Million copies to EU ALONE for its launch

Its sold a 1/3rd of that so far

Hummmmm...

EU: 3.5M shipped = 2.5M sold.
US: 1.5M shipped = 1M sold.
JP: 1M shipped = 500k sold.

Still missing 1 million units.

first week or December?

Fallout 3 shipped 5 Million at launch.....took it between half a year to a year to get there

This seems to be a new strategy devs use

It probably maximises PROFITS since I hear retailers buy "reshipments" at lower prices

I'm overestimating a little but my first week prediction is more like:

EU: 2.0M
US: 700-800k
JP: 500k

Not far.