Despite what series creator Kazunori Yamauchi had to say to us on the topic during E3, Spanish newspaper El Financiero quotes SCEE executive James Armstrong as stating that Gran Turismo 5 (the full, real deal – not Prologue 2 or some-such) will be released in Europe "by Christmas 2009." This is, of course, concerning a series that's been historically fast and furious loose with release dates.
GTPlanet – which is part of the chain of custody on this rumor – speculates that, if true, we could see a summer 2009 release for GT5 in Japan and a late 2009 / early 2010 launch in the West. This scenario would certainly follow the staggered roll-outs of previous Gran Turismo titles to a (Model) T.