casetracker_comment_driven (CTCD for short) allows for CCK fields to be added to Case Tracker and tracked in the comments in a manner identical to how standard cases are tracked. This is achieved by using the Comment Driven module to track changes made with each comment and merging the Case Tracker table with the Comment Driven table to make them appear as one.
This method should work for anything that can be tracked with comment_driven. Hypothetically, this includes the title, taxonomy terms (tags) and almost any other field. This functionality has not been tested yet.