I just finished "What is Redaction Criticism?," by Norman Perrin.
Perrin begins with some history which takes us back to ~1850 and the Marcan hypothesis (Mark was written first and used as source material for Matthew and Luke). Where Mark, as a source, has post-Easter theology is where redaction criticism kicks in and says the Marcan writer has polished the script a bit. If I have this correct one looks at Mark and assesses what may be Marks theological thrust (for the Church(es) in Rome, for instance) from the sources he drew from. Then one can more easily assesses Matthew and Luke, where Mark was the source material, and see what their individual theological urgency may have been. Once one is working out of Matthew and Luke (assuming a two source hypothesis) one can begin also to say what Q said and the theological thrusts Matthew and Luke made based on Q (Quelle). Good intro book to a type of higher criticism.
diggidy damn- this was enthralling. its from 1970 so academic conversation has moved on a wee bit, but an excellent intro to redaction criticism- can speed through it in a couple hours.