We created a series of Visio 2003 stencils last September to support our series of articles on BPMN. Anthony Britton has created a Visio 2002 version of the stencils for people who do not have Visio 2003 (or Visio 2007).
Thanks Anthony!
The Visio 2002 stencils for BPMN can be downloaded here, or from the original article. Any future updates will be recorded in the original article (this post will not be updated).