Donnie Berkholz presented at FOSDEM 2013 with various X.Org statistics and a look at the health of the development community. Not counting just the X.Org Server but also related components within the X.Org umbrella, the pace of development appears to be on the decline.
Berkholz, a long-time X.Org and Gentoo contributor and employee of RedMonk, also reiterated facts about the X.Org Foundation not being accepted to the Google Summer of Code project last year and other shortcomings. His development statistics on X.Org slowing down in the past few years incorporates not only code activity but also mailing list messages, contributor count, and other metrics.