i am sorry but having 7 monitors is unnecessary for 99.99999% of the people are you are not the .00001%. I mean, have it if you want it but deosnt make it less useless and pointless. Monitoring tools and IM should take half a screen at most.
Depends on the person and the job - in theory only 1 monitor is *NECESSARY* for any person. When I testing OS installs and applications with virtual machines and emulators like Bluestacks I can run out of monitors pretty darn quickly, especially if I'm testing graphical stuff that requires certain resolutions (testing commandline stuff in Linux is trivial with SSH). When an application needs to be tested on as many as 6 separate OS's for compatibility it's amazing how much you hate WINDOWS-TAB after a short period of time. As for my monitoring tools they take up nearly an entire monitor by themselves as there are apps watching the video cards (I have 3 GPUs), CPU, RAM, and UPS.
In terms of gaming I could probably get away with 6, although the 7th monitor is nice to have as it holds the desktop icons and taskbar (3 for Eyefinity, 1 for monitoring, 1 for game notes, and 1 for a browser when I get stuck). Certainly I needed less than 6 when I had my LLL/PLP because I was gaming on only 1 monitor.
To each their own, but given how much the price of LCDs have dropped (especially big ones like the 27") and the availability of > dualmonitor video cards I expect to see a lot more rigs like this pop up. I've already help build 4 of them for independent music studios, video editors, and one very insane special-effects artist, all friends of mine who saw my little setup and instantly wanted it.