This package is included in main ubuntu repo.
I don't know why apt didn't find it .
What version of ubuntu you have 10.10 or 10.04 ?
Try to check /etc/apt/sources.list file, and search if there exists :
deb http://us.archive.ubuntu.com/ubuntu/ maverick main
if you have installed 10.10 version or
deb http://us.archive.ubuntu.com/ubuntu/ lucid main
if you have 10.04