Good news for AdWords API junkies, you can now differentiate between negative keywords in your keyword structure reports. According to a post by an official AdWords representative in Google Group, Google has added a KeywordIsNegative column to the Keyword Structure reports.
Jeff from the AdWords API Team explained:
This column can be used to determine whether a given keyword in the report is "normal" or negative, and resolves a long-standing deficiency that made it impossible to distinguish normal and negative keywords in Keyword Structure reports.
You wont find information about this new feature in the AdWords API documentation, just yet. But Jeff explains how you can get at this data in the Google Group thread.
Jeff shares that there is more to come, "this additional column is just the first step being made to address that feedback."
In other AdWords API news, it seems like in some cases, negative keywords are being returned in a different report named KeywordVariations. Jeff confirmed this is a bug and he hopes it will be addressed shortly.
Forum discussion at Google Group.