This is just a quick update to let you know that Alien Arena 2011 (7.50) which was released last week is available for Ubuntu 10.04 and 10.10 users @ PlayDeb.
To install Alien Arena 2011, you'll have to download and install THIS .deb - it will automatically add the PlayDeb repository to your software sources. Then simply visit the Alien Arena page at PlayDeb and click the install button.