The last Namco arcade game I saw was Soul Calibre II. And that's a while now. The latest Sega arcade that I know of is Daytona USA 2.
It's not like because of Triforce that Sega and Namco should now rush to start making new arcade games. F-Zero AC is something I absolutely DIE TO PLAY, and really, is Star Fox 'Armada' an arcade game? I know it spells Nintendo's return to the arcade, but what else will Namco and Sega make for Triforce? Seriously? The only thing I see is that they port their old games over. Daytona 1/2 would be cool, Time Crisis 1/2, Crisis Zone would be even cooler. That reminds me, we need some light-gun games for Gamecube! And seeing as Namco made a gun of it's own for PS2, they could do one for Nintendo!.