Good news everyone, the Eclipse PDE team finally made the visualization component available for everyone.
To obtain it, use the Install New Software wizard in Eclipse and point to the correct repository.
The plan is to ship this as part of the Eclipse Helios release.
In its current state, the tool visualizes OSGi bundles only. There is some discussion about adding support for features and packages. If you’re interested in contributing to the visualization tool, please let the PDE team know.
If you find bugs or have feature ideas, please enter them in bugzilla.