Views 2 serves pages with for non-existent URLs instead of presenting a 404 Not Found Error.
A view with page display path set to blog creates a valid link at example.com/blog. This will show a list of blog posts, with an individual article at example.com/blog/new-article. However, an accidental link to example.com/blog/accidental-link will provide content from example.com/blog instead of the expected 404 Not Found Error, since no valid content exists there. This is a usability as well as SEO issue.