I run an SGI 1600SW flat-panel from NVIDIA cards (GF3's). The 1600SW has a 16:9-ish ratio (actually it's 1600 x 1024 native). The Linux drivers support this resolution quite happily, and have done for some time.
I've driven the monitors both via DVI and analogue VGA without any issues.
I presume the resolution of the plasma screen will be somewhat lower than this? If so you might be into making up custom modelines, but that's pretty easy to do (did it before 16x10 was a "standard" mode the drivers knew anout).