Rockstar has confirmed to videogaming247 that the originator of this story claiming the 360 version of GTA IV is "superior" to the PS3 outing is not Rockstar North's Neil Corbett.
"Regarding the [story]," said a Rockstar spokesperson. "I can confirm that this is not Neil Corbett from Rockstar North that has been posting on rllmuk."
The poster from the forum had said that the Xbox 360 version of GTA IV "has the smoother framerate and far faster loading times (without any installing) but the PS3 version does have that warm feeling with bleached out sunsets and the like".
The forum post also said that the "extra content of the 360 version is significant but nothing like an ‘extra Island’ at all- as the lead platform it is currently the superior version however. Just you wait until your first windscreen-flying experience.”
So now you know. As Big Phil says, "You shouldn't believe everything you read on the internet."