To add to the references I gave for Scott Plutchak's Bishop-LeFanu lecture, John Hewlett has posted the latest Current Literature column for the edition of the Health Libraries Group Newsletter of 2004 December, vol.21, no.4 to lis-medical, including two articles on the informationist:
Cunningham,D.J., Kronenfeld,M.R. The informationist: a debate. Journal of Hospital Librarianship 2004; 4(1): 1-15.
Burdick,A. Informationist? Internal medicine rounds with a clinical medical librarian. Journal of Hospital Librarianship 2004; 4(1): 17-27.
Also significant as this is John's valedictory column after 23 years of keeping UK health librarians up to date.