Comment 5 for bug 658768

Natalia, you can't reproduce in a fresh maverick environment because dpkg-maintscript-helper (which causes the failure) was renamed in dpkg 1.15.7.2 and 1.15.8.4ubuntu3 is available in maverick.

The only way to reproduce is either to upgrade from lucid (and ensure that dpkg is installed after ubuntu-sso-client which can be tricky because many packages pre-depend on dpkg), the other way to reproduce is to install dpkg < 1.15.7.2 in maverick and then upgrade both dpkg and ubuntu-sso-client.