Should be no surprise, but the Architectural refactorings on Enterprise Library 5.0 move away from static and instance factories to containers for configuration. The only reason why you saw both Unity and the various static and instance factories available in Enterprise Library 4.x was just to provide an intermediate step to get people to the container-based approach.
Hopefully you are jumping up and down for joy with this news, because this means that ObjectBuilder will no longer be used to wire up the application blocks in Enterprise Library 5.0. Instead, you can pick the container of your choice, Unity, Castle Windsor, Ninject, Autofac, etc. to be the container and main configuration mechanism for the application blocks. Enterprise Library 5.0 will use IServiceLocator as a way to work with other containers besides Unity.
Not only will the container-based approached make it easier to work with Enterprise Library 5.0 in your applications, but it should also hopefully help you create custom application blocks and application block providers.
For more information on this Architectural Refactoring of Enterprise Library 5.0, make sure you check out the following post.