Someone who talks non-stop about work especially to people who aren't coworkers. Common offensives: constant use of lingo and acronyms that others don't understand or care to understand, name dropping of coworkers that others don't know or care to know, going into way too much details about specifics in their work day.
So my new roommate is a work talker. She told me last night in painful detail about how the copier broke at her job and how Susie and Jim (who recently broke up) had to push the reset button and after three times it still would not work. They had to call the service guy who came to fix it and turns out it was the toner because Susie had made so many copies last week when she was working on the S.C.A.N.T project.