API access to the SCM repository's build identifier for a given build

It would be very useful if a build stored the SCM build identifier (i.e. SVN revision, CVS date, P4 revision) that a given build was checked out with.

This could then be used by

• anyone wishing to recreate a given build
• an integration server to build and deploy the software when the build succeed (our environment is complex, and the servers doing CI are not in the same location as the integration servers which live in our datacentre). While we could cobble together

This is related to my commentary on BAM-61; although reading that is not mandatory to understand my request.