The Acropolis team just announced that the core Acropolis concepts will be rolled into future .NET Framework releases. As Glenn just announced, the patterns & practices team will develop WPF Composite Client guidance. This is not a new version of CAB . It is an entirely new set of libraries and guidance, built from the ground up, targeting development of new WPF Composite applications. We'll be working with both the UIFX and WPF teams, the same people who build the platform.
For more details on our plans check out Glenn's blog post.