The Ubuntu package seems to be 0.8.29
http://packages.ubuntu.com/search?keywords=calibre and the latest at
http://calibre-ebook.com/download_linux is 0.8.31 as of this writing. The easiest way to install is to use the package manager in ubuntu and simply click install. But as Calibre gets new releases quite often and thus the ubuntu repository may lag a little you may like to install it yourself. Check the instructions at
http://calibre-ebook.com/download_linux and ask again if there is something missing.