The gran turismo HD concept demo will be launched on the Playstation Store from the 24th of December 2006.

The details albeit in japanese are here
http://www.gran-turismo.com/jp/sp/d374.html

And more interestingly Yamauchi san also has posted his comments there saying that Gran turismo 5 is being given preference over gran turismo HD and he expects that to be released earlier.

Anyways lets be content with Santa yamauchi's gift of a demo this christmas. By the way its been quite some time since we have heard of that GT-Mobile... maybe its no more on cards for the PSP???