Unfortunately, often the barrier to entry is high, because communication is poor. Information tends to flow through a small group, and if you're not in that group, you're out of the loop. This stopped me from contributing to Firefox for years, and my college roommate is a Mozilla employee.

But recently, I finally just got something done. Push hard, ask questions. People are often glad to have help, but pleas for general help go unheard. Direct communication is best. The guy in IRC asking questions will get ignored, but the direct e-mail, often, doesn't.

Best of luck.