Yep, it's still on the todo list. The javascript that sets the cookie is in the ubb_jslib.js file.
Just played with it, expiring my cookies many times, and it seems that it works properly if you change Line 256
From:
expires = 365 * 60 * 60 * 24;
To:
expires = 1000 * 365 * 60 * 60 * 24;
(added the 1000 ms as described above)