Read this forum post for details: Future development - Unreal3.2 & Unreal3.4.
If you're interested in becoming a developer, contact Syzop (allow 48h for a reply). In general, though, we would want to see some contributions first.
You can visit the development IRC channel at irc.unrealircd.com/#unreal3-devel
Note that 95% of our communication takes place on the bugtracker, where bugs, new features, and code rewrites are discussed!