Check out the official reflection guide at http://docs.scala-lang.org/overviews/reflection/overview.html. Thanks a lot to Heather Miller who took time to assemble it!
Other sources available are: 1) the slides from one of my talks, 2) Daniel Sobral's blog posts, 3) Scaladoc links on the stub pages accessible via the URL provided above, 4) and Stack Overflow answers. I might've missed something here, please let me know if that's the case.
