The rate of development is staggering. For a huge, complex project of this nature to keep releasing so often, mostly high-quality releases, and display such a high work-rate consistently is simply amazing.
What is even more amazing is that despite all the flame-fests on mailing lists and the loneliness factor - you cannot do kernel development while socialising - the number of kernel developers continues to increase. And not merely from companies - where people are recruited to work on the kernel because of the company's interest - but from outside.
This, remember, is happening at a time when many other free and open source software projects are struggling to find people who can be added to the developer ranks.
To date, from the 2.6.11 release, a total of 855 companies have made contributions. For the latest release, 226 were involved. This means that they hire hackers to work on aspects of the kernel which suit their own interests.
But whether people are from companies, fall into the unknown category - where no company affiliation can be determined - or are working on their own, they are all managed well by one person who has created a hierarchy based on meritocracy that results in amazing output. That, in itself, is another very remarkable result. The word dysfunctional is never heard when discussing the kernel project.