Sorry to say that TrackballWorks is incompatible with Mountain Lion for me. I recently did a Clean Install of ML, and from the get-go my preferences for my Expert Mouse Trackball were "forgotten" after a restart. I could only get my preferences back by opening the Trackball preference pane, an annoying chore at launch. The software worked fine in Lion.
Kensington Support use to be stellar. Several years ago I could reach a knowledgeable tech person by phone in 5 minutes. Now, they have enabled a byzantine anti-support system that is outsourced to India. Even though they were already aware of the problem, they required 4 screenshots of "About This Mac" panes uploaded to their site BEFORE they would even talk to me. Two weeks of on-again off-again replies finally led to the revelation that a software fix was necessary. Their solution? "Don't restart your computer". A software fix was projected for the "first quarter of 2013". This is for software that hasn't been updated since July of 2011.
I have been a huge fan of Kensington trackball hardware for over a decade, but alas the current owners are not committed to software support, or a streamlined and useful customer support system. I am hoping they will wake up and make changes for the good in a timely fashion.