I took the liberty here to translate the complete expression, as found on the ProZ Homepage, since I think that the expression "language workplace" makes a difference. I also took the liberty to translate in a more concise way, even if it alters slightly the meaning (although I tried to keep the meaning as closely as possible), because I feel that this should be something of a catch phrase.

(If you still want just the above expression as is, I would translate it by "En tete de file des postes de travail sur le Web" or "Le chef de file en milieu de travail sur le Web" or "the leader en milieu de travail du Web".)