If like me you prefer to keep your projects tidy using solution folders like this:
When you come to create a list definition (from a content type) from one of your content types you’ll get this:
(There are no content types in the project)
Even though clearly you have defined content types in your solution.
It’s a bug and one Microsoft are aware of and working on. Nevertheless, you need to get this working and you don’t want to mess up your tidy project to do it!
The solution is simply to move (drag and drop) the content types project into the solutions root while you create the definition, that way the wizard (which is obviously not coded to look in folders) will find the project and you’ll be able to create your list definition. Job done!
Andy Noon - SharePoint since 2001 