Is Wikipedia Production Slowing Down?

Until recently I had assumed that the growth of content on Wikipedia was exponential. It certainly looked that way over its early history, and other kinds of “knowledge publication” like scientific journals (or the Web) have shown consistent exponential growth. But it looks like there was a peak-drop-flattening that started around Spring 2007. I wrote short report on my blog, with some pointers to others who have also seen this “anomaly”, but I haven’t seen a satisfactory explanation for why this has happened. I’m interested in hearing from anyone who might have a bit of insight about what may have precipitated this change in the dynamics of Wikipedia content production.