Logolounge the 2011 report
A single client having a series of logos is absolutely nothing new. This is a time-tested solution to maintaining a core, consistent visual identity while focusing on specific divisions, products, or services. What is remarkable is the sudden ubiquitous deluge of these family marks.
In some cases, there is a parent mark that the family is constructed to relate to. Yet in others, every logo is of equal importance, and there is no single flagship logo. Nickelodeon exemplified this years ago with a common typographic solution knocked out of an orange field of fill-in-the-blank. But that solution relied more on the volume of solutions rather than the specificity of topic.
One consideration might be the expansive adoption of icon sets for mobile devices or Internet apps, which have built greater consumer familiarity with the concept of allowing a core icon to be redressed to take on multiple focuses. Color-coded series can be the least effective of these if the audience must memorize a system. Equally dangerous is the consumer not recognizing that a single mark is part of a greater system because of lack of context.