Developers
Start here New Developers Welcome Pack
General
Building QGIS
The UsersCorner has a list of sites providing various rpm and deb packages that satisfy qgis build dependencies.
Build notes for developers
SVN trunk
Building with CMake - build guide for all platforms
QGIS 0.8 and earlier
Coding Standards and Bug Hunting
Coding Design Discussions
Coding tutorials
Help on writing custom apps with QGIS API
Help on writing plugins
API Documentation and source profiling
Miscellaneous
Guidelines for Preparing A Release
I have just added this section and the documents are still in preparation.
SourcePackagePreparation (platform independent)
DocumentationReleasePreparation (platform independent)
PostReleaseChecklist (press announcements etc)