Callisto Simultaneous Release
The goal of the Callisto Simultaneous Release was to release ten major Eclipse projects at the same time. Callisto was a definite success.
We did this simultaneous release to support the needs of the ecosystem members who integrate Eclipse frameworks into their own software and products. While those product producers naturally accept the ultimate responsibility for their customers' experiences, Callisto's goal was to eliminate uncertainity about project version numbers, and thus to allow ecosystem members to start their own integration, cross-project, and cross-product testing efforts earlier. Callisto was about improving the productivity of the developers working on top of Eclipse frameworks by providing a more transparent and predictable development cycle; Callisto was about developers helping developers serve the whole Eclipse community.
While Callisto was about the simultaneous release of ten projects, it was not a unification of the projects - each project remained a separate open source project operating with its own project leadership, its own committers, and its own project plan.
From The Ten Planets: Callisto seems to have little internal structure; however there are signs from recent Galileo data that the interior materials have settled partially, with the percentage of rock increasing toward the center.