Plato 1 was released in November 2007, based on the revision of the Planets Preservation Planning Workflow as described in Planets Deliverable PP4-D1, which is based on earlier work in DELOS.
A description of the workflow can be found here.
Since then we have been working on extending the functionality and concepts of Plato.

Plato 2 has been released October 2008.

The current version of Plato is 2.1 which was released in November 2009.

• Objective tree editors and knowledge base. We have redesigned the user interface for the objective trees and come up with a much easier to use and much faster editor for the knowledge base.
• Jhove. We have integrated JHove, including a neat visual side-by-side comparison feature for migrated sample objects to support visual evaluation.
• Quality-aware migration services We have made a prototype registry containing quality-aware migratino services available through Plato, featuring automated evaluation of some of the requirements. These migration service measure quality and performance (time and memory) and provide this information together with the result. Corresponding publications about this technology can be found on the documentation page.
• Navigation structure. We have introduced a home screen providing a central point of entry.
• Executable preservation plan. Plato 2.1 creates an executable preservation plan in XML, which can be run in the Planets workflow execution engine.
• Service Integration. Updated access to Planets migration services.
• Scalability. Previously, it was not feasible to upload large sample objects to create a preservation plan, due to memory limitations. We have worked on this issue and are now supporting sample objects sets up to (roughly) 200MB per plan.
• Policy definition. You can now define your policies once and each preservation plan you create will be using these policies.