Unsubscribe from Group via Profile in My Account does not work

See this forum post:
http://forum.civicrm.org/index.php/topic,11216.0/topicseen.html

To recreate w/ sample data in a 3.0.3 install -

• Add the "Groups" field to New Individual profile and update that Profile setting to Used for = User Registration, My Account.
• Make sure Permissions for Authenticated Role include the usual recommended - profile listings and forms, access all custom data, make online contribs, register for events
• Register as a new user and signup for 2 sample maillilng list groups
• Then log in as this user (they will only have Authenticated role) and go to My Account
• Edit the Profile and uncheck on of the groups and hit Save
• The group u uncheked is still checked (and if you look at the contact record as an admin, that contact still is subscribed to 2 groups.

I then tried Kirk's 'hack' of giving 'edit all contacts' to authenticated - and had the same result. The user is able to unsubscribe if given that permission. However, this is not a valid workaround since we don't want to give that perm to all authenticated users. It does indicate that the bug is related to permissioning though.