On same hardware and under gutsy tribe-4 with all updates, I see the same thing. switching to vt1 and back to 7 leaves me with a black screen, but the mouse still moves.
After disabling compiz (add intel driver to blacklist in /sur/bin/compiz) xrandr transforms such as xrandr -o left leave the screen in a normal usable state.
On same hardware and under gutsy tribe-4 with all updates, I see the same thing. switching to vt1 and back to 7 leaves me with a black screen, but the mouse still moves.
After disabling compiz (add intel driver to blacklist in /sur/bin/compiz) xrandr transforms such as xrandr -o left leave the screen in a normal usable state.