Hello,
If you are using SQL 2008 R2 with ConfigMgr 2012 RC, you`ll probably receive this error "Report Builder 2.0 is not installed as a click-once application on report server"
ConfigMgr 2012 is designed to work out of the box with Report Builder 2.0
You’ll need to set a registry key to name the RB 3.0 application manifest. The key in question is “HKLM\Software\Wow6432Node\Microsoft\ConfigMgr10\AdminUI\Reporting\ReportBuilderApplicationManifestName”. Change its value from “ReportBuilder_2_0_0_0.application” to “ReportBuilder_3_0_0_0.application” on any machine from which you want to launch RB 3.0.
Then start the Configuration Manager Administrator console as administrator and it works.
Have a nice day