In the beginning of 2013, we have published a paper covering the state of the art of macrology in Scala 2.10. It provides an interesting perspective and an up-to-date interpretation of some of the originally envisioned use cases for Scala macros.
Our more recent talk "What Are Macros Good For?" (click here for the video) describes and systemizes uses that macros found among Scala users. The thesis of the talk is that macros are good for code generation, static checking and DSLs, illustrated with a number of examples from research and industry.