A quick read on Lifehacker this am, and I crossed this great article about the myth of monitors/screen real estate MORE is better.
Noticing the funding behind most of the more screens are better for productivity, (Apple, NEC) along looking how things are working in my environment, I am unsure of who to believe.
Realizing this is about screen real estate and not the number of monitors and how they are deployed. This is where the productivity gains are being realized. Having 2 reports open, allowing quick and easy review has been quite a boom to production.
The most notable boom to production has been tying 2 computers to one keyboard and mouse, (teleport - mac) thus harnessing two CPU's reducing the corresponding downtime.
The distraction issue is still prevalent, (twitter, email, imessage) either way!