I have written quite a few posts on the subject (here and here). It basically means that volatility in GDP and inflation has become lower over the years. Hence there is a huge research on the factors responsible for the same.
White points to 4 possible reasons for GM- monetary policy, domsetic deregulation, global savings and globalisation. Yellen adds:
Because no single hypothesis adequately explains the full set of “stylized facts”, Bill advocates a global aggregate demand-aggregate supply approach in which all four explanations matter to inflation to varying degrees and at varying times. Demand-side factors, driven mainly by tighter domestic monetary policy, were central to the decline of inflation in the 1980s and 1990s. Supply-side factors, associated with both domestic deregulation and globalization, as well as lower aggregate demand associated with excess global saving, all have played a role in restraining inflation more recently.
However, Yellen says she would add more importance to monetary policy and less to globalisation. Yellen provides a lot of references on the subject as well.
Overall, a nice read.