- Open a Windows Explorer and make a duplicate of the report that you want to use as a template.
- Rename the copy (suffix with template?)
- Remove objects unique to the report and leave elements for all reports.
- File > Save selected item as...
- For SSRS 2008: Save in the folder: "C:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE\PrivateAssemblies\ProjectItems\ReportProject"
- Done!