Identities of anonymous posters in an Advanced forum can be revealed by any member who subscribes to that forum as the link in the email notification will be a link to the poster's profile.

1) Add an Advanced forum with optional subscription and anonymous posts enabled.
2) Start a new post as any user on the course.
3) Login as student 1 and subscribe to that thread.
4) Login as a student 2 and make an anonymous post to the thread.
5) Log out of all Moodle sessions
5) In 30 minutes student 1 will receive an email notification of the anonymous post.
6) In the line in the header that says by Anonymous User, click the text 'Anonymous User' (note that it is a link to a real user profile in the course)
7) In the Moodle login page that appears, login as student 1 who has subscribed to the thread.
8) You will see the course profile of student 2 who has made the anonymous forum post.