For Introductory Purposes

Check out:

This article by Bill Jones, a practical guide to using RS in a production environment (not just some shmancy sales pitch, like most info out there).

This introductory article (targeted at people who can already use asp.net)

And moving on to BLOGS

The best so far has been: "Chris Hays's Reporting Services Sleazy Hacks Weblog" (Not surprising that it is so useful, it's written by: "the guy who gets to take the credit and/or blame for designing the Report Definition Language.")

Measuring and improving performance (of Microsoft SQL Server Reporting Services) at Tudor's Reporting Services WebLog

Apparently "Tudor is the lead developer for the Reporting Services product and thereby an instrumental part of its design and development."

Bryan's WebLog: Reporting Services - Design, Deploy, Deliver

The Reporting Services category of Tara Duggan's blog.

And it must be added:

Enjoy Every Report: Kent Tegels' Reporting Services WebLog

But don't neglect the newsgroup:

microsoft.public.sqlserver.reportingsvcs