Implementing Data Security in SSRS Report Model

This is a good blog on explaining the Data Security within SQL Server Reporting Services (SSRS)

Bob's SQL Reporting Services Blog : Implementing Data Security in a Report Model

We are also looking at doing our own custom data security, so we can do it through our own groups and permissions within our application.

Passing Multi-Value Parameters to Subreports

When passing a multi-value parameter using the Expression Builder it will automatically add the Parameter!Name.Value(0).  If you strip the (0) then it will work.  This expression returns the first selected value. 

Parameter passing from master to subreport : SQL Server Reporting Services : SQL Server : MSDN Forums