I dont think nvidia support 3x vertical monitors, only horizontal.
AMD does support a vertical configuration.
These are the options aviable in Nvidia surround
Source: http://www.pcper.com/reviews/Graphics-Cards/NVIDIA-Surround-and-3D-Vision-Surround-Revealed
I dont know if you can rotate a surround display so as to use the portrait mode, then rotate by 90degrees or not.
As for AMD Eyefinity, these are the config options that can be achieved.
Source: http://widescreengamingforum.com/article/amd-eyefinity-faq
EDIT: ATI also supports 3x in vertical mode, and 5x1 in landscape mode to a max res of 8000x900