I think a member should be responsible for doing the editing and posting and be assigned for a 4 week period based. Perhaps alphabetically by last name to keep it simple.
More, I think the posts should be put on either 90minds.com or a new private blog that members use either the direct rss feed or chimfeedr. Super easy to consume it in your own rss to email campaign. chimpfeedr works with any solution like aweber, constant contact etc, its not exclusive to mailchimp