My guess is that we are still one year away from GT5 being released. And I have no problem with that, my life doesn't depend on gaming.
Meanwhile, this also means that games like NFS:Shift, Supercar Challenge and V8 Superstars Racing will get some needed "breathing space". Good for them.
Back to GT5, again I see jaw-dropping graphics, but that's the GT trade-mark (and their curse too). A trailer doesn't tell you anything about physics, I can only hope they take that aspect at least as seriously as they do graphics.
So, what's new? very important stuff:
a) damage engine;
b) rally stages (although we see two rally cars do battle

)
c) NASCAR (but limited to 16 cars)
d) a "hint" of day/night transition (could mean nothing, but could mean a lot also)
Unrealistic bit [joking] at 0:34, the pigeons don't get scared when all the SuperGT Japanese cars enter the street! PD, get your act together and make those pigeons fly, or else people won't buy the game !!!!!!

[/joking]
Back to serious stuff ... my "short list" of demands remains unanswered in this trailer. It concerns mostly endurance racing and I WANT this:
a) day/night cycle (hinted, but not confirmed)
b) variable weather
c) ability to save mid race (in the pits, as an example)
d) Spa-Francorchamps