In that case, maybe you should contact the Ubuntu package maintainer of OA.
Or maybe they just wait and re-use Debian packages, I'm not sure.
Or install OpenArena without using the package system, downloading it from the official website, and run it with a command, quite simple too
I dunno if there is a way for developpers to be advertised of new versions. I doubt there is a mailing list for OA, there is a "news" forum which does it all, maybe some RSS or Atom feed could help a bit, but this job is mainly the package maintainer's responsibility, and with an appropriate bugtracking system new versions of OA should be quickly available.
I never made .DEB files, it requires some specific guidelines i'm not (yet) aware.