Hello Brad Perniciaro,
Currently Telerik Reporting supports report parameters, which can be used to customize the report before it is generated. In this version it is up to the developer to create a GUI for assigning report parameters with values.
But for one of the next versions we will provide automatic GUI generation based on defined parameters. In this way, you will only have to define the desired report parameters and your customers will be presented with a GUI to set whatever values they want, i.e. the last n records, a record with a certain date, etc.
More on parameters can be found here
the Telerik team