Getting Involved with the Community
As a developer, your first (and best) way to get involved with the community is to use the Eclipse IDE for your development and explore what the many Eclipse projects have to offer you and your fellow developers. Let your interest areas guide you: if you're interested in modeling and visual editing, consider the Eclipse Metadata Framework (EMF), Graphical Editing Framework (GEF), and Graphical Modeling Framework (GMF) projects; if you need to generate reports, consider the Business Intelligence Reporting Tools (BIRT) project. There are many projects; as you get more familiar with the community you'll develop a natural tendency to explore them all.
Don't wait too long to get directly involved with the community. The "newbie" news group is monitored by seasoned Eclipse users and developers who are happy to answer your questions. Be sure to read "How to Ask Questions The Smart Way" by Eric Raymond and Rick Moen before you post; well formed questions tend to be answered while poorly worded ones are not. If you want to keep track of conversations occuring with the Eclipse community (primarily between developers), consider adding yourself to one or more mailing list. Each project has its own mailing list. Some mailing lists (like cross-project-issues-dev) span projects and are a good source of information concerning the integration of the various projects.
Perhaps your most valuable resource as a member of the Eclipse community is Bugzilla. Bugzilla is your main interface to the developers; it is how you contribute directly to projects. As the name implies, Bugzilla is primarily used to report bugs. But it's used for more. You can request new features and even pose questions through Bugzilla (though questions are probably better suited for the news group). Be sure to read How to Report Bugs Effectively.
If you want to keep informed about the progress of bugs through the system, you can register (by configuring "User Watching" in the Email Settings) to be notified when a bug is created or modified. This is a great way to be a "fly on the wall" as bugs are worked through the system. You can learn about the process while you learn about Eclipse just by watching these notes.