Diplomacy is the title of the second "mini-expansion" for Sins of a Solar Empire, which will be unveiled to the assembled fans and press at Penny Arcade Expo 2009, which runs from September 4-6, 2009. More details should be expected at that time, but for now a blog post by Brad Wardell outlines PAX plans that include showing off Diplomacy, their upcoming Elemental, and new stuff being added to Demigod. Thanks Big Download.