A great post by Helen Barrett that very clearly describes, in detail, the two distinct facets of e-portfolios, as process and as product. The rest of the site contains great examples, explanations and ways of using Google Docs (and many other tools) for both facets.

I particularly like https://sites.google.com/site/eportfolioapps/overview/blog-entry-eportfolios-and-googleapps which nicely captures the inevitable confusions that occur when institutions try to harden the many processes and kinds of product in the e-portfolio field by selecting tools to support them.