For the migration, below are some areas of concern that would be great to have some answers for. Ideally, it would be great if there is a tool that would read a Seam 2 project folder and list the changes that should be made.

What should be changed from view layer (in my case Richfaces)? Currently xhtml files use Seam 2 schema. We have some quite complicated components and pages and make heavy usage of Ajax. JSF 2 adds a lot of functionality for Ajax and it'll be good to know which UI components should be updated/changed.
How to migrate navigation and pages.xml to Seam 3 and CDI to work with JSF 2 properly? What about page parameters migration if any.
URL rewrite migration.
How to migrate bean and deployment configuration from Seam 2 to CDI and Seam 3. For example, components.xml and other config files like hibernate or persistence.
How to migrate tests:

UI tests with SeamTest. I noticed there is not a good way of doing UI tests in Seam 3 unless I'm missing something.
Integration tests that use an in-memory db. I know Arquillian in Seam 3 would take of this.

How to migrate from Seam 2 specific areas to Seam 3. For example, in my project we use email templates heavily from Seam 2.
Localization and internationalization migration. For example, what happens to message bundles and StatusMessages from Seam 2.
Security migration, I use authenticate-method and did not find its equivalent in Seam 3. Seam 3 Beta release is missing security documentation.
How to migrate the integration with open ID from Seam 2 to work in Seam 3 and CDI. Open Id support in Seam 2 was lacking and did not support important features like attribute exchange. People had to write custom code and it'll be good to know how to migrate custom code to Seam 3 and CDI.
How to migrate components that deal with external services. For example, my project integrates with Facebook using Facebook java API which depends on Servlet (not java script API). What would be the migration plan? It would be even better if Seam 3 would offer a way to integrate with common services like Facebook.
How to migrate outjected objects. CDI uses @Produces annotation but having few concrete examples part of migration guide would make developer's lives much easier.
How to migrate conversational and transactional components? Again, having few concrete examples would great to accomplish this.