For those who don't know: http://en.wikipedia.org/wiki/Colors_of_noise
Basically, in an environment where there are other noises that can lead to distraction, these noises DO help concentration and productivity by drowning out the distracting noises.
Programmers such as myself cannot focus when conversations are constantly happening near by - but if I have music or if another programmer has noise canceling headphones on, work can be done.
It also depends on the kinds of work. Mechanical work, work requiring pre-scripted movements or little cognitive processes are probably not impacted by the implementation of colored noises. Factory workers don't get faster if the entire factory becomes quite.
But anything that requires mental concentration and a line of thought will benefit from these things that help "shut out" things that might get in the way.
Disclosure: These are my opinions and I am not an expert in the fields of acoustics, electrical engineering, physics or psychology.