I am not alone! Other people are using OneNote as an ePortfolio tool. This is pleasing as I was a little worried that the lack of mention of OneNote in the course and associated discussions might mean it was an inappropriate tool choice (despite my feeling convinced that it does what I need it to). It's been good to do a little web research, and find out what other people are doing.
So, firstly I found the OneNote and Education blog - not surprising that they would have something to say about ePortfolios there then. This blog talks about a maths teacher using OneNote to teach classes, give homework, engage students in collaborative assignments, store grades, give feedback etc. Critically, every child in that school has a laptop for their work.
Next there is the Language Education and Resource Network which included a conference presentation titled 'Use OneNote as ePortfolio to Increase Interaction and Collaboration', and has made the PowerPoint of the talk available. Again, the focus of this is more on class teaching, collaboration, electronic grading and integrating distance and present learners, than on a more personal ePortfolio, but great to see another example.
There's even a sample ePortfolio available from Microsoft. It includes sections for each individual pupil with homework, quizes and tests subsections, a group work space, and plenty of space for pupils to do their own work as they see fit. It's not a portfolio structure that will work for my own current H808 needs, but nice to see a suggestion.
It has to be said that all of these examples are quite different to how I expect to use my ePortfolio, but they illustrate several important points. Firstly, ePortfolios are many things to many people - there really is no concensus on the term. Secondly, OneNote has the toolset and capacity to assist in the gathering, selection and storing of ePortfolio artifacts. Thirdly, it's a good choice for me!