Actually they are on my desktop. I have a 2.5 Meter long desk with an L bend in it where it goes around the walls of my office.
I have the middle display right where the bend is then the other two displays on either side and I sit at the bend. I sit as close as I did with my older 20" displays to be honest. I guess my head is about a foot and a half away, maybe less. You get used to the size.
Also something to keep in mind when using Eyefinity or Surround is that games do not really support that extreme field of view so what you find is the two outer displays show a stretched and unnatural view of things. So when you're gaming in these triple display setups you don't turn your head at all you just focus on the centre display while the extra two displays on the sides stay in your peripheral vision.
This means you get the full immersion of surrounding almost all of your vision. It's great in some games for example I'm a big lover of Team Fortress 2 I play it all the time and it works fantastic in this game because the amount of stuff you can see at the side of your player is greatly increased. Again you're not turning your head to look at the sides, but having it in your peripheral allows you to see other players that you might have otherwise not noticed without the added panels. Here is a screenshot to illustrate what I mean:
http://dl.dropbox.com/u/7299662/ctf_turbine0023.jpg
In the above screenshot (which is from my system) you can see that in the centre you get a crisp clear, everything in proportion single-display sized view of what's happening. Then at the sides you can see everything is stretched and looks funky but I'm still getting a ton of extra information from the sides, things that if I was in single display mode I wouldn't be able to see at all.
A lot of people think when you activate surround you get the same single display image but rendered larger to fit the extra two side displays but that isn't the case, on the centre display you get the exact same image that you would get on a single display setup then you just get extra stuff on the sides that usually looks funky like in the image above.
I've yet to play a game in surround that doesn't have that funky distortion on the sides but it doesn't really bother me as again you only focus on the centre display. I think if I were to lay the monitors completely flat against a wall and sit far back so that all three displays where in my eye line I'd go nuts. It would definitely look very strange. I think this technology is best served when you're sitting right up close in-front of the displays in a curve.