Claire I like the idea of optional attendance. University students have a lot going on, and sometimes it's difficult to make it to class.
As long as students are held accountable for the information they're supposed to learn, I don't see why they should have to attend every class session, especially for classes that meet multiple times a week.
Andrew I have to disagree with Claire. I think that class attendance policies foster another important kind of accountability. They teach discipline and responsibility. Many of the jobs that university or trade school students will pursue after graduation have their own attendance policies, so students should see class attendance as good preparation for entering the workforce.