See in the comments he states GT4 had ZERO options for screen configuration. Thats a little worrying...
Multiscreen options in GT3 and GT4 were just "sub-option" of LAN (iLink in GT3) mode, where you could set up additional consoles to act as "spectators" screen.
And since you could choose any view in spectatator screens, for 3-set multiscreen set-up people used front-view and both side-views.
If you had enough hardware, you could go crazy, with setting up up to 6 consoles in multiscreen all around you, where you could have "back" 3 consoles to act as backside-left, full-back and backside-right views.
However, notice that you could use multiscreen (spectator) only in Arcade modes - Time Trial or LAN (iLink) race - and if you had enough hardware (6 consoles, 6 sets...) you could set-up 2x3-screen for 2-player ultimate fun.
If multiscreen in GT5 will be supported in all game modes, than we can expect adjusting options. Also, inclusion of interior-views will also demand some adjusting, especially because RHD and LHD cars on one side, and McLaren F1, open wheels and protoype class cars on the other, would seek for some adjusting due to change of POW.
We'll know soon enough I hope.