The Collaborative International Dictionary of English v.0.48:

Conversationalist \Con`ver*sa"tion*al*ist\, n.
   A conversationist.
   [1913 Webster]

WordNet (r) 3.0 (2006):

conversationalist
    n 1: someone skilled at conversation [syn: conversationalist,
         conversationist, schmoozer]

Moby Thesaurus II by Grady Ward, 1.0:

18 Moby Thesaurus words for "conversationalist":
   chatterbox, collocutor, colloquialist, conversational partner,
   converser, dialogist, discourser, interlocutor, interlocutress,
   interlocutrice, interlocutrix, palaverer, parleyer, patterer,
   sayer, speaker, talker, utterer