What has Ubuntu contributed to the Linux Kernel?

I'm not sure this is really the best way to measure Ubuntu's contributions to the free software world, but it's easy enough to look:

• List of commits in mainline from @canonical.com addresses.

• List of commits mainline from @ubuntu.com addresses

There's some data provided by Greg Kroah-Hartman in his talk "The Linux Ecosystem, what it is and where do you fit in it?" for the Linux Plumbers Conference 2008. While you can find a synthesis of the talk here, the slides are not available, so you can watch the video.

These are figures from 2008, but I'm sure these had not changed much:

    Amateurs: 17%
    Red Hat: 11.9%
    Unknown: 8.3%
    IBM: 7.8%
    Novell: 7.3%
    Intel: 4.4%
    Consultants: 2.1%
    Oracle: 1.9%
    Linux Foundation: 1.8%
    SGI: 1.8%

And, after a correction about the number of patches canonical has contributed, they appear with a 00.10068% of all of the kernel development, or 100 patches(remember, 2008).

AFAIK, every patch comes with an the author's associated email, which allows to know the origin of it (@canonical.com, @debian.org), so there is a difference between Debian and Ubuntu in this matter. Also, take this with a grain of salt, there's more than a way to measure contributions to the Linux ecosystem than just measuring the kernel.