There is no word yet on what his role will be, but if you aren't familiar with Aziz, he's from MTV's sketch comedy show, Human Giant. This article also states that it's unlikely anyone from The Office will be leaving the cast for the spinoff.
Spoiler TV forums recently had a vote as to which new shows they would add and The Office got voted in! There are two sub-forums one for spoilers and one for no-spoliers just show discussion