Caching of build trees
It can be interesting to cache and store a dirty build tree for later reuse.
The idea is that if the build tree itself, with object files and timestamps in tact could be cached and shared, then this could allow incremental builds at a later time on another host.
One could then, for instance, desire to hack on WebKit and create a workspace using the last known build of the correct cache key, so after modifying some file, only part of the webkit build would have to run.