Right now, projects act as virtualenvs, each project contains and build its dependencies. This is intended for fast evolving libraries. Imagine you have 5 similar projects all depending on the same library A, version 0. While working on one of those projects you can make a modification to A and publish a new version, an API breaking modification. The other 4 projects will continue depending on version 0, and will not break. When you move to those projects you can easily update their dependencies and fix the breakages.
You can share the same library among different projects straight ahead with sym links if working in linux, not working by now in windows.
For very stable, large projects that can be installed system-wide, it could be more convenient to depend on the installed version. CMake allows this very easily via FindXXX(). You can install system wide the binaries with CMake install, or you can even use CMake scripts or biicode python hooks to automatically download and install system wide those libraries. Check, e.g.:http://www.biicode.com/diego/opencvex, OpenCV is managed with a biicode python hook and installed system wide.
At this moment there is no "local" publication, and if you want to share that way among projects, yes, you have to go over the biicode cloud servers, simply with "bii publish".
However, we are transitioning to open-source. We will probably release first the client code, then we will release a server that could be deployed in-house. Not implemented yet, but a future feature is that this server could act as a proxy to the cloud one, you can publish to the local instance, but read from the cloud one. With a local installation of this server, you will be able to publish locally.