Is there a way to view in the report a list of UNOPENED? In some cases it might warrant a phone call or some other measure if the list is checked and a certain individual did not open it.
You could easily create a segment that contained all the people we could not record an open for - see http://www.campaignmonitor.com/blog/archives/2007/02/creating_and_using_segments.html for help with segments.
Also, be sure to read up on how open rates are measured - it is possible some people did open your email but were not recorded because they did not open the images, for example. See http://www.campaignmonitor.com/blog/archives/2007/01/all_about_email_open_rates.html for more on that.
Ted, one final way you can get to this data. Head into the reports for that campaign, click on the Recipient Activity Report and then change the drop down to only show those that haven't opened the campaign yet. You can also easily export this to Excel.
Make sure you also keep in mind Mat's point about how open rates are only estimates.