I've just been trawling amazon to see what Montalbano delights are in store. As well as the UK edition of The Potter's Field in May 2012, also listed are the US editions of The Age of Doubt (May 2012) and Hunting Season (Jan 2013).
In addition McFarland are publishing a companion guide, Andrea Camilleri: A Companion to the Mystery Fiction by Lucia Rinaldi, in July 2012:
Publisher's Blurb: This is the first comprehensive reference work in English dedicated to the writing of world-famous Italian mystery writer Andrea Camilleri. It includes entries on plots, characters, dates, literary motifs, and themes from the bestselling author’s detective stories and television crime dramas, with special attention to the serialized policeman Inspector Salvo Montalbano, Camilleri’s most famous character. It also equips the reader with background information on Camilleri’s life and career and provides a guide into the writings of reviewers and critics.