Bots (robots) can use the Pandorabot for chatbots and you can host your own. I guess its bases on the ELIZA. Bots are not against the TOS (Terms of Service) of Second Life but you have to identify this avatars on the SL webpage as Scripted Agents (i prefere to use this word more than “bot” in this days).
“Pandorabots is the place where you can create and unleash virtual personalities. Pandorabots is an experimental software robot hosting service based on the work of Dr. Richard Wallace and the A.L.I.C.E./AIML free software community.”
In short, with creating a login and a own bot database the Chat Pandorabot can be trainded and an avatar-bot (scripted agent) can chat with this content.
On the simulation Ouvroir at the North/East island there should be a sitting elephant avatar which uses Pandorabot. http://slurl.com/secondlife/Ouvroir/225/219/22