This is very intersting stuff..
My requirement is: I have one report and I want to add this report as report template in list of SSRS templates, so that I neither need to rewrite my report nor need to add sub reports.
Answer is: Just create your standard template report and Once your are done with your report, just copy and paste your standard report at following location:
C:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE\PrivateAssemblies\ProjectItems\ReportProject
You are all set.. You will see your report as standard template in BIDS(Business Intelligence Development Studio)