i'm using the analog(vga) th2go with a mini-displayport to vga adapter on a unibody 17" macbook pro and a nvidia mac mini. it works without any additional software, but only in 2400x600 because of limitations in the aforementioned adapter. i even tried a third-party adapter, same thing.
tools like switchresx didn't solve that resolution problem either.
anyway, in 2400x600 it works perfectly well.
i wasn't able to try a dvi th2go or displayport th2go yet. anyone else?
another interesting observation: using the mini-dvi output at the mac mini and adapter it to vga gives you the 3072x768 or even 3840x1024. but the graphics inside that little box won't cause you much fun in this configuration...