Sorry for the delay... I was sick with a broken dev machine, and without our source tree for reference, my knowledge on the subject is, well, not quite there...
Oxygen was setup for continuous integration before I started, so I know the "how" it works, but not the "why."
Before I started, I never had continuous integration setup (wow, I didn't know what I was missing!), so I don't know if my previous organizing methods would have worked so well... (even if I did really like them)
On to the point...
We use subversion for source control and have a build server running CruiseControl. We try to keep the build machine clean, so we're confident we have the project dependencies under control. The build machine does not even have Visual Studio installed -- just the .NET SDK so our projects can be built on the command line.
As for the development tree, its pretty simple:
1. Project Root
a. lib (Oxygen libraries)
b. tools (3rd party libraries) -- references like mbunit or rhinomocks and tools needed to build (like nant, msbuild...)
c. src (project source code)
There are some other folders in the root, but they are specific to the project, like documents or media... All references are to assemblies in lib or tools, never the GAC, this minimizes dependencies that need to be installed on the build server.
The only other file of note in the project root is our build file, which is a NAnt script. This script has several targets, like compile, unit-test, setup-dev-environment, install, cruiseconrol, etc (such a pain to write, but well worth the effort!) The cruisecontrol target, compiles, runs tests, builds installers, deploys installers, runs metrics, sends us result emails and has our bunny tell us updates.
So, "D", I hope this satisfies your curiosity about our development tree! If you have more specific questions, please let me know :)