Should Contributors Be Able to Access wp-admin?

I’m using a vBulletin bridge with WordPress and am wondering if that plugin is causing permissions problems, or if contributors are supposed to be able to access wp-admin.

You can see here what members are able to access:
http://www.westernstreet7.com/images/mhc.png

Although it doesn’t seem they can actually delete or edit other peoples’ posts, they can add posts to the approval queue, see other peoples’ posts, etc. Is that normal?