It came from JKR's diary section on her home page on May 14 2007. You can find them all posted here: http://www.hp-lexicon.info/about/sources/jkr.com/jkr-com-diary.html#13

But the one in question reads as such:
May 14, 2007

A couple of weeks ago (April 28th, if you want to go and search the archive) the Potter fansite The Leaky Cauldron posted an editorial on potential spoilers for "Deathly Hallows". It made me laugh, but I was also incredibly moved and grateful.

We're a little under three months away, now, and the first distant rumblings of the weirdness that usually precedes a Harry Potter publication can be heard on the horizon. The Leaky Cauldron's early mission statement on spoilers (ie, don't, and we're not putting them up if you do) is deeply appreciated by yours truly.

I add my own plea to Melissa's for one reason, and one only: I want the readers who have, in many instances, grown up with Harry, to embark on the last adventure they will share with him without knowing where they are they going.

Some, perhaps, will read this and take the view that all publicity is good publicity, that spoilers are part of hype, and that I am trying to protect sales rather than my readership. However, spoilers won't stop people buying the book, they never have - all it will do is diminish their pleasure in the book.

There will always be sad individuals who get their kicks from ruining other people's fun, but while sites like Leaky take such an active stance against them, we may yet win. Even if the biggest secret gets out - even if somebody discovers the Giant Squid is actually the world's largest Animagus, which rises from the lake at the eleventh hour, transforms into Godric Gryffindor and... well, I wouldn't like to spoil it.


Anyways, point is, as a few of you have mentioned, it seems to have been intended as a joke. But you know how things go in the fanfiction world. I bet there's a fic out there using Godric Gryffindor = Giant squid as the formula for a cringe-worthy story.


--Boo

'It was revealed by J.K. Rowling, while making a joke, that Godric Gryffindor is still alive: he is the Giant Squid that lives in Hogwarts' lake, and thus makes him the biggest Animagus in the Wizarding World. At the eleventh hour of each night; the Squid transforms back into Gryffindor, who wanders the school grounds before returning to his Squid form. This explains why the Squid, despite its dangerous-looking appearance, is kind and gentle in nature (revealed when he saved Dennis Creevey from drowning).'

She did say it while joking though, so it's possible it may not be true. I'll have a look around for the interview though. I'll keep you posted.

This is... weird. Fascinating if it's true, but... where did you find it? I drop into mugglenet every day and I haven't heard a word about it.

Er, really? o.O

*resists urge to pounce on usage of 'begs the question'* Huh. Interesting. It would explain so much, and yet leave so much unexplained. You found this tidbit where?

This has my curiosity peaked.

Heavens, that epilogue must have been only the beginnings of the evidence that she'd snapped.

How on earth did none of the students rampaging around out of bed late at night not run into him?

How did he live this long?

What's the *point* of this concept?

JKR, you're mad.

Arti, you got a source for this? If it's an interview or something I would rather like to read all of it.

Y'know, I totally would have picked a lion for his Animagus form, since all the symbolism points that way...

...but then again, what says courage and nobility like the avatar of Great Cthulhu himself?
Gryffindor? Squid? I seriously fail to see a connection here, despite the fact that I like squid.

But hell, why listen to me? I'm just a Ravenclaw, babbling on about logic in the corner over here... I mean, that's pretty cool, but the giant squid?

... and wave a sign saying [Citation needed].

No, I did not know that.

hS