So some good news bad news.
Bad news is, the NVS 810 does NOT work with the native drivers. The Good news is DOES work with the web drivers!
There is one weird caveat that I suspect will not apply to others, but you should know. I have 6 30" cinema displays that show 2550x1600. Any of the monitors that I plugged into the DisplayPort to DVI adapters (provided) would not show up in full resolution. Furthermore, I have one display that uses a display port, but for whatever reason, the USB connection from the apple DVI to mini DisplayPort USB is dead (basically means you cannot dim that screen from the System Prefs). That monitor, also, will not show full resolution. My guess is their DVI adapters are not dual link so you'd need the apple Duallink DVI to minidisplay port adapters.
My guess is if I replace my now ancient 30" displays with some more modern 4k screens, it would work fine, but there you go.
This card is actually a really great card in a lot of ways. Not only is it a single slot, it doesnt even need one of the power cords, it runs fully from the PCI slot. While it's not super fast, it's faster than say the 5870 by a decent bit, and leaves you 3 full slots free for other things. So if youre in need of a video wall project of some sort, I could totally see slapping 2 of these in and getting 16 screens (or I guess even 4 cards and getting up to 32 screens).