In the default ubercart product type definition for the image field, using a clean multi-site install, the "image path" for the product was set by default to the same value as Drupal files directory. So, it creates a sites/somedomain.com/files directory within sites/files. So, I end up with ...

/sites/somedomain.com/files/sites/somedomain.com/files

I'm assuming this is just a multi-site issue. Running PHP5, Drupal 5.7, clean install. Easy to fix, just an fyi.