Nvidia's 3D Vision Surround is said to work over two cards in SLI with different monitors connected to each card and be backward compatible with their current generation. ATI said they couldn't do this because of some sort of synchronisation issue.
Are ATI still working on this or are their fundamental differences between SLI and crossfire that will always prevent such a setup?
just to comment a bit here. nVidia's solution looks more and more like SoftTH, it's likely that they made something similar to SoftTH and has got SLI to work with it. ATI's solution is all hardware based, so that's why (by theory anyway) eyefinity would have those sync issues.
Hell they had that issue at the unveiling of Eyefinity with there X-plane Demo wall where they we running 4 copies of Xplane at the same time and the top left quadrant would move first, than the others would follow.