Interaction Designers: What We Are, What We Do, & What We Need to Know 

A 2001 presentation by Robert Reimann and Jodi Forlizzi titled Interaction Designers: What We Are, What We Do, & What We Need to Know (ppt) provides a good overview of interaction design.

Reimann, Robert and Jodi Forlizzi. IxDA Resource Library (2005). Presentations>User Centered Design>Interaction Design