A good place to start is by joining Peter Blackburn for his session titled Introduction to SQL Server 2005 Reporting Services in the evening of 24th April in Manchester.

The session is described as follows:
What We Will Cover
Introduction to SQL Server Business Intelligence (BI)
What?s new in SQL Server 2005 Reporting Services
Report Lifecycle

Demonstrations in this Session
Viewing Reports as an End User
Designing and Publishing Reports as an End User
Designing and Publishing Reports as a Developer
Managing Reports Using SQL Server Management Studio
Embedding Reports in a Windows Forms Application

Peter's also presenting Advanced SQL Server 2005 Reporting Services in the evening of 31st May @ the Microsoft Campus in Reading.

The session's described as follows:

See advanced techniques for building reports with Microsoft SQL Server 2005 Reporting Services and the Microsoft Visual Studio-based Report Designer. Topics in this sessions include: how to use the built-in expression language, report parameterization (data driven, multi-valued, and hierarchical), supporting multiple data sources (including relational, multi-dimensional, and XML), and making reports interactive. Learn about the new features in Microsoft SQL Server 2005 for report designers, receive a walk-through of sample reports and discover tips and tricks for using the Report Definition Language (RDL).