I was reading this thread: http://wordpress.org/support/topic/multiple-roles-for-a-user because I have a situation where multiple roles are needed.
the install is a multisite install with some custom roles and a bbPress forum plugin install. The forum requires a Moderator role. So, here is a situation where you have a many-to-many relationship need for roles, as my client doesn't want to have to log out from the administrator role to take on the moderator role.
COMMENTS FROM PLUGIN WRITERS
The bbPress forum specifically states that, "Under the hood, WordPress comes with support for users having multiple roles, and this is a perfect use-case for needing that functionality." http://bbpress.org/forums/topic/roles-and-capabilities-in-bbpress-2-2/
So, does it or doesn't it?