Catherine Tate will make her return appearance sometime during the second half of Season 8, reprising her role as Nellie Bertram, who was interviewed for Michael Scott's job during last year's season finale. She is recruited as a special project manager working for the corporate office by close friend and Chairman of the Board, Jo Bennett (Kathy Bates, who'll not be seen this year).
This is what producer Paul Lieberstein (aka Toby) had to say about bringing on British comedianne Catherine Tate in a larger capacity.
"Catherine is hysterical. We introduced her briefly in last season's finale and knew she had to be a part of the show somehow. We'll meet her again as corporate special projects manager, and her relationship with Robert California (James Spader) will be far from professional."