I work for a very large organization.  I am trying to research who
"owns" learning management systems when they are deployed in such
organizations.  By "owns" I mean who is primarily responsible for the
system - who is makes sure it is working, upgrades it, answers
customers' questions, etc.   Is it the Human Resources/Training
organization or the Information Technology/CIO organization?  One
company that does learning management systems is Plateau, but there
are others.  I would like to have "roles and responsibilities" type
information.

This varies from one organisation to another.  What is quite common
now is for a specialist company to host the LMS for you, so in this
case, they would "own" and "manage" the system - excpet for certain
simple tasks like adding new users, which someome within youe own
organisation would usualy be trained to do.

In one project I worked on we implemented a Global, customised LMS,
but hosted by the LMS provider company who were essentially in charge
of the system, keeping it running, etc..   At the customer site the IT
deparment were responsible for the system.  The admin tasks such as
creating users were sometimes done by HR, sometimes by the IT
department - this was different for each geography/country/entity.
Its really down to you to decide how it best fits within your
organsational structure - but bear in mind that owning an LMS system,
although it brings many benefits, will be seen as a cost to that
department or function.  Many of the reports generated by an LMS will
be based around who has used the system, what they have done on it and
what department or cost centre they are from, so the LMS owners can
charge back to them.
Does that help at all?