The biggest announcement of all TGS so far has been Monster Hunter 4 for the 3DS. People have been making a big deal that Capcom didn't say it was going to be exclusive to the 3DS. The same thing happened with Monster Hunter Tri on the Wii, Capcom never said exclusive but the game never did come out on any other platform. When Capcom announces a game and only shows it for one platform, that usually means at least a timed exclusive.
The trailer is done with real-time graphics on the 3DS but really doesn't indicate what the game will actually play like. I don't think we will be running away from Monsters the entire time in a "Monster Hunter" game. The announcement is certainly a huge step in the right direction for Nintendo and the 3DS in Japan.
The United States has a big holiday to be excited for as well with Mario Kart 7, Super Mario 3D Land and the announced 3DS update for new Street Pass games & 3D video capture.
A huge day for Nintendo!