From a blog post I wrote for the Wolverine Pride Blog - http://truckeepride.blogspot.com/2011/05/designing-eportfolio-assignment.html
Students in my Web 2.0 Class develop ePortfolios to demonstrate and reflect on not only their learning in my class, but in life. They will each leave my class with a tool that they can continue to update so that they can not only reflect on their learning and successes but share them with others. Think college admissions, perspective employers, or future class or work projects.
Here is a resource article from the Learning Objects Community to help teachers think about how they can use ePortfolios in their work with students.Designing an ePortfolio Assignment