Is there any way to have multiple managers and/or departments in active directory?
Active directory is Microsofts implementation of the LDAP standard. It conforms to the LDAP v3 standard.
So, yes, there is a way.
You can create OU's in Active Directory, here is an example...
http://helpdeskgeek.com/networking/setting-up-organizational-units-in-active-directory/
No, I'm afraid that's not possible. According to the standard Active Directory schema, the "manager" property of a user is a single-valued property, e.g. it can contain only a single value (or none).
Check out Richard Mueller's site with lots of great overviews of all AD attributes and more - excellent resource for AD related questions.
You could potentially extend the AD schema - that's always possible in LDAP - but it's not a very simple and awfully easy to understand process, I'm afraid......
Marc