Image via WikipediaRedshift is an observation about the growth of computing demand of applications. If your application's computing needs are growing faster than Moore's Law , then color it red. If they are growing slower, or about the same, color it blue.
Redshift applications are under-served by Moore's Law. The simple and obvious consequence is that the infrastructure required to support redshift apps needs to scale up. That is, the absolute number of processors, storage and networking units will grow over time. Conversely, infrastructure required by blue-shift apps will shrink as you get to consolidate them onto fewer and fewer systems.
Refining just a little, redshift apps appear to fall into three basic categories:
Sum-of-Band Width. Basically, these are all of the consumer-facing apps (think YouTube, Yahoo!, Facebook, Twitter) that are serving the bits behind an Internet whose aggregate BW is growing faster than Moore's Law.
Sum-Prise. These are software-as-a-service style consolidation of apps that, at most enterprises, are blue. But there is a huge market over which to consolidate, so growth rates can become quite large (think eBay, SuccessFactors, Salesforce.com)
HPC. Technical high performance computing was the pioneer of horizontal scale. For a good reason: halve the price of a unit of computing or storage, and most HPC users will buy twice as much. These apps are expanding gasses in the Nathan Myhrvold sense (think financial risk simulation, weather simulation, reservoir management, drug design).