there is for the blackberry and your BES admin can give it to you along with the connection settings. i have yet to see an install or bridge for the PlayBook, but i remain hopeful.
I am too looking for a PB app for office communicator, MOC, and looking high and low.
I found that the company Mitel has the "Unified Communicator Advanced for BlackBerry PlayBook" that they say is a communications platform for this very thing.
From what I can see is that this is an enterprise level software and I think, but not sure, that you have to have their desktop or server software running as well in order to extend the services to your PB. But again I am not sure.
I cant find a download link for it as I think it is a full system and not a stand alone app.