This paper describes the results of a collaboration between the University of Queensland, the Australian National University and the National Library of Australia which has developed and deployed an automatic obsolescence detection and notification service (AONS) for digital collections. AONS can be configured to run over different types of collections of digital objects—either institutional repositories (DSpace or Fedora) or Web archives such as the National Library's PANDORA ('Preserving and Accessing Networked DOcumentary Resources of Australia') Archive. This work represents a real-world implementation of the obsolescence detection and notification service originally developed within the University of Queensland's PANIC Project. PANIC (Preservation and Archival of New media and Interactive Collections) was a prototype system based on a semantic Web services architecture which was designed to semi-automate the preservation of digital collections. This paper describes how AONS can be configured to automatically monitor collections for format obsolescence and streamline the subsequent migration of 'at risk' digital objects to current recommended formats, enabling their long-term preservation and accessibility.