ASCD: Capturing the Wisdom of Practice: Professional Portfolios for Educators. Go to ASCD Portfolio Readings index at:
http://www.ascd.org/cgi-bin/AT-Readingsearch.cgi

The Schoolteacher's Portfolio: Issues in Design, Implementation, and Evaluation. Ken Wolf, Ed Leadership, Oct 1991.

Teacher Portfolio Assessment: http://www.ed.gov/databases/ERIC_Digests/ed385608.html