Unfortunately, this is not supported in the current version but a similar feature is scheduled for version 3.1 (Mid September). We call it Site Template and it will be a feature of the Project Manger. You will be able to modify supplied templates or create new ones. When you create a new project ,you will be able to specify template for that project which will include predefined Themes, Pages, Controls, Content and etc.
We plan to extend this feature in version 3.2 so that any existing Sitefinity website can be exported to a template.
For the time being, you have to either copy the projects manually or you can change the default empty project located in [installation path] \ telerik\Sitefinity3.0\ProjectManager\EmptyProject.
the Telerik team