Yes that is what I'm telling you
The 5870 has 2 DVI inputs, 1 HDMI, and 1 Displayport, so you can potentially run 4 monitors off of one card. Just from some quick searching I've found that all you need to set up Eyefinity is a monitor with a displayport connection, or a displayport adapter, for the native (wrong word, but the monitor you use to set everything up) monitor.
So using a 5870, or if your loaded, a 5970, you can run an insane amount of screens, at an insane resolution, for an insanely low price (minus the 5970....) compared to an Nvidia set up. Since you only need one card, so less cards = less heat, less power, less cost.
Youtube video I found :