I've just made the first ever release of gnome-devel-docs. This recently revived module contains documentation for people developing against our platform. Currently, it contains the Platform Overview, the GDP Handbook, and the GDP Style Guide. A rough list of planned documents can be found here:

http://live.gnome.org/DeveloperGuides

Get it here:

http://ftp.gnome.org/pub/gnome/sources/gnome-devel-docs/2.19/

If you want to help us provide rock-solid developer documentation to match our rock-solid platform, join us in #docs on irc.gnome.org, or send an email to gnome-doc-list@gnome.org.

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Shaun