multiple organizations and users

Any solutions for multiple organizations?

The same content applies to everyone but contacts,events etc would not be shared.

Example:
Organization ABC with users 123
Organization XYZ with users 345

Organization ABC contacts etc are seperate from Org XYZ. In another example how could one allow a single drupal site with multiple roles and users have access to their own sets of CiviCRM Contacts?

An assumed solution would be the db tables for org ABC would be prefixed: abc_contact, xyz_contact