The magazine chose to not explain this in its pages, too, introducing Russ by having his Editor's Note in lieu of Jim's show up a few issues ago. These Editor's Notes have tended to the vague and big picturish in any case.
Publications are usually horrible about explaining their own affairs.
The New York Times gets positively terse when forced to write articles about laying people off at Time Digital, for instance. In that light, those kinds of announcements read very much like press releases, which is unfortunate for the reporters conscripted to write the stories. There's no response to it, which would have the right opportunity to clarify Jim and Russ's roles. There's got to be some back story. I checked the company's site, and, despite the awful, unbypassable Shockwave opening, the rest appears legit.