Yesterday, bit-tech.net says (in Gran Turismo PSP still in development) Despite repeated delays and rumours of cancellation, Sony has promised that the PSP version of Gran Turismo is still in development.

This Week, Shacknews says (in Sony Boss Likes Xbox 360, DLC Exclusivity) It's in Polyphony Digital, they're working on it ... they've had to focus on finishing up Gran Turismo on the PS3 side," he said.
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And info@download-psp.com (download-psp.com) from PSP Games says (in TGS 2008: Gran Turismo PSP still coming, says Yoshida) From TGS we finally get an update, no matter how small, on the Gran Turismo game for the PSP.Wait, there's a Gran Turismo game for the PSP? Yes, for those who forgot or don't have a clue since we hardly get any updates on it. ...

And Ars Technica says (in Sony: Gran Turismo still coming to PSP)  MA - Oct 10, 2008
They have been working on Gran Turismo 5 Prologue and Gran Turismo 5 for PS3, so they've had to focus on finishing up Gran Turismo on the PS3 side. ...

And feedsportal.com says (in Gran Turismo is still coming to PSP - honest) Sony boss says they've been busy with other things

And MaxConsole.net says (in Still no word on when we will see Gran Turismo for PSP) Sony Worldwide Studios boss Shuhei Yoshida was recently asked if Gran Turismo for PSP would finally see a release in 2009. Yoshida said he could not comment and that GT 5 for PS3 has slow down the PSP development. Gran Turismo creator ...

And The Net from 360derajat (Blogspot) says (in Gran Turismo PSP is coming, says Sony News - Eurogamer) Gran Turismo PSP is coming, says Sony NewsEurogamer, UK - "They have been working on Gran Turismo 5 Prologue and Gran Turismo 5 for PS3, so they've had to focus on finishing up Gran Turismo on the PS3 side," he ...

And Eurogamer says (in News: Gran Turismo PSP is coming, says Sony (PlayStation Portable)) It's just taking a bit of time.

Last Week, tlozwarlock from Kotaku.com says (in New Cars For Gran Turismo 5 Prologue) Polyphony Digital is a development team. GT5 Prologue is essentially a beta GT5. They're all working on it. And don't expect a much different experience for the full version. You're going to get maybe 100 to 200 cars and 20 to 30 tracks ...