I downloaded passwordsafe-ubuntu-0.6.0BETA.amd64.deb on Ubuntu 11.04 (64-bit) and did "gnome-open ./passwordsafe-ubuntu-0.6.0BETA.amd64.deb" (note: no sudo used). That opened up Ubuntu Software Centre which had an "Install" button, clicking on which nothing happened. I saw some policykit related errors in the console.
Then I ran the same command with "sudo" and the Install button worked, but threw up the attached warning. I also saw these in the terminal:
2011-07-24 12:04:31,456 - softwarecenter.backend - ERROR - error in _on_trans_finished 'Error: The package is of bad quality
The installation of a package which violates the quality standards isn't allowed. This could cause serious problems on your computer. Please contact the person or organisation who provided this package file and include the details beneath.
Lintian check results for /home/saurav/work/passwordsafe-ubuntu-0.6.0BETA.amd64.deb:
warning: the authors of lintian do not recommend running it with root privileges!
E: passwordsafe: dir-or-file-in-tmp tmp/pwsafe.desktop
E: passwordsafe: dir-or-file-in-tmp tmp/pwsafe.png