Laura Wingerd's Practical Perforce focuses on one SCM system in particular (Perforce, which I highly recommend), but has a lot of good material that is generally applicable to any sufficiently-powerful SCM system. The last chapter, on 'staging streams', was enormously helpful for my team when we wanted to get a good branching setup for frequent releases.
The entire second half of the book (starting with a chapter titled How Software Evolves, which gives you a good idea of the general thrust) is very good reading for anyone involved in a project that is at all long-lived or complex, regardless of whether or not they are using Perforce. The author is one of the chief architects of Perforce, and she really understands SCM from front to back.