Don't know much about that many monitors, I know there's a HD 5870 Eyefinity 6 Edition that can run 6 monitors.
Going for a HD5970 to ensure that 6 monitors will be an option. I need to know one thing .. will I be able to run applications on diff screens like photoshop on one monitor, the tools on another and on 4 of the other screens I want to run Light Room or a Dia show, is this possible?
The new ATI EyeFinity 6 supports up to 6 screens. I've also seen that you can have them working like I want to. So now it's just the config around the GFX, going to take obisidian's config and tweak it a bit.