Professor Yorick Wilks, an OII Research Fellow and the PI of the EU Project on Digital Companions, has a concise and powerful overview of what he calls ‘machine conversationalists’ in a recent issue of Science (9 November 2007: Vol. 318. no. 5852, pp. 927 – 928. DOI: 10.1126/science.1148895). It is entitled: Is There Progress on Talking Sensibly to Machines?
If you would like a concrete sense of an early version of a digital companion — what Yorick calls an ‘initial incarnation of a companion’, see: http://www.nabaztag.com and adopt a rabbit. And for more general information about the Companions Project, see: http://www.companions-project.org/