Some time ago I did a blog entry for SQL Server Integration Services packages as a data source for SQL Server Reporting Services reports. You can find this article here.
This feature relies on a data processing extension that is explained in detail here (http://msdn.microsoft.com/en-us/library/ms345250.aspx).
Due to security reasons, this feature has been deprecated and removed in SQL Server 2008 R2. If you want to create and consume a more complicated data extraction you should think of either creating a stored procedure (eventually with CLR, depending on your needs) which prepares the data or kick of a SSIS integration package which creates the relevant data you can consume this data with any supported data provider.