This package was from Debian Lenny, and uploaded only for Ubuntu 10.04 to 11.04 AMD64 release. It's because that those distributions does not have partimage amd64 version in the resitory:
http://packages.ubuntu.com/search?keywords=partimage
Here we put an older version so that if a newer version existing on its own repository, it will be used.

Sep/05/2011.
Steven.