I have seen no official statements from the Braves one way or the other and have a lot of sources that I check for this stuff.
Edit: That said my personal opinion is that Sosa is done as closer...but that's just based on what I would do if I were managing the team and not anything concrete that has been said.
Hope springs eternal
grows like ivy on the vine
then dies in the fall
--Haiku for a Cubs Fan, The Loveable Losers