Not sure why anyone would want to emulate a TI anyhow. (HP partisan here!)

I know the HP48GII, 49G+ and 50G are all 200 MHz ARM chips (factory clocked at 33, 75, and ?75? MHz for battery life) emulating the old Saturn processor of the HP48S(X), 48G(X+), and 49G. And all outperforming the native one, of course. So a 48 emulator should certainly be possible, though x48 is probably nowhere near as good an emulator as the one in 49g+ rom.

Are all late-model TIs run on 68K cpus?

Also, you said it wouldn't show the buttons; would it work using xrandr for portrait mode?

EDIT: Just got back from watching the video; that's no more than a factor of 2 slower. Not bad, I'd consider it useful, especially if I could get an HP49 ROM in, but metakernel would probably run nicely.

EDIT: http://www.hpcalc.org/details.php?id=3689 is a 48 emulator benchmark utility; if you've still got x48 around, results would be nice. And emu48 for Mac OSX exists; the port to a different OS hopefully indicates proper separation of platform-specific stuff, so it should be possible to port to Linux/GTK+.