Today while trying the new report builder 2.0 i came across an intresting issue. The new report builder is unable to connect to a SQL Server 2005 Report model. Report Builder 2.0 is supported only with a 2008 server (it uses the new RDL format which is not supported in 2005). So too bad for those of you who want to use the new report builder with your existing environment.
Read the Microsoft reply here: