I'm a huge fan of the Valdemar books and I didn't know Changing the World released last December. It was such a pleasure to come across it!
The collection is edited by Mercedes Lackey and the first story is by her. The other stories are written by a number of different authors, but feature the Valdemar world.
If you haven't read this series, I think you'd be fine starting with either the Magic, Wings or Arrows trilogies.
Your turn - what've you been reading and loving?