There are some genuinely enlightening revelations from the census. For example, though GNOME is a "volunteer" project, and 70% of the developers identify themselves as volunteers, 70% of the commits are made by paid developers. Independent volunteers still represent the biggest block of developers, but as former Red Hat employee Greg DeKoenigsberg is eager to point out, Red Hat developers are responsible for 16% of committed code, the biggest commercial contribution, and much bigger than GNOME mindshare-leader Canonical (with 1%). Many of the other top commercial developers are from consulting firms that rely on GNOME.
The Census takes an interesting look at module-by-module contribution, looking at which ones are primarily volunteer-maintained, which ones are collaborated on by competitors, and which are maintained largely by one commercial entity. It's a fascinating read.