Jane I'm currently reading a Murder of Mages, and enjoying it every bit as much as I did the Thorn! I can't wait until The Alchemy of Chaos is available.
Marshall Maresca There is! A Murder of Mages is not the sequel, as it follows different characters in a different neighborhood of Maradaine, but there will be more Thorn books. The sequel to Thorn, THE ALCHEMY OF CHAOS, will come out in early 2016.