Does uPortal support LDAP authentication?
Yes. The problem, however, is that there are dozens of possible ways to do an LDAP authentication for uPortal and hence what is available now may not be useful for your campus. But there are a few Universities now who are using uPortal in conjunction with an LDAP server to authenticate users. There is a reference implementation included with uPortal which handles authentication of users to the portal from information stored in an LDAP server.
The good news is, even if this reference implementation does not totally meet your needs out of the box, the ISecurityContext API is highly pluggable in uPortal and you are able to plug in your own authentication provider without pervasive modification.