Co-Authors Plus makes it easy to add multiple bylines to a given post, and has full support for custom post types. Out just a moment ago, v2.6.2 has the following improvements:
- AJAX user search matches against first name, last name, and nickname fields too, in addition to display name, user login, and email address.
- Comment moderation and approved notifications are properly sent to all co-authors with the correct capabilities.
VIP Code Wrangler, Daniel Bachhuber breaks down some of the enhancements and bug fixes available in the most recent update to Co-Authors Plus.