You can allow some groups to comment and not others.
On the left side of the Blogs
page, there is a
navigation pane with a Blog Control Panel
Access that link, and then check the box marked "Allow Comments to Be Posted"
under the heading "Default Entry Options." Then scroll down to the section
"Permissions and Privacy" and uncheck the boxes associated with the groups
you prefer not to allow to comment
on your blog. You can also limit specific
people from commenting by putting those individuals on your "ignore" list in
your My Panel options. The default setting in your
Blog Control Panel prevents "ignore list" members from posting. Another
limitation feature is in the Blog Control Panel at the top, under "Default Entry
Options," you can check the box marked "Moderate Comments Before Displaying."
Comments will display only if the blog owner approves them. Blog owners also
have the ability to delete comments after they are posted.