Comment 8 for bug 438077

From the latest screenshot:

"Software updates are available for this computer"
https://translations.edge.launchpad.net/ubuntu/karmic/+source/update-manager/+pots/update-manager/pl/242/+translate

#: ../UpdateManager/UpdateManager.py:500
msgid "Software updates are available for this computer"
msgstr "Dostępne są aktualizacje oprogramowania"

"If you don't want to..."
https://translations.edge.launchpad.net/ubuntu/karmic/+source/update-manager/+pots/update-manager/pl/243/+translate

#: ../UpdateManager/UpdateManager.py:501
msgid ""
"If you don't want to install them now, choose \"Update Manager\" from the "
"Administration menu later."
msgstr ""
"Można zainstalować je później, wybierając pozycję \"Menedżer aktualizacji\" "
"z menu Administracja."

Again, this shows that at least the strings are correctly imported (present in the Launchpad template and translated) and exported (present in the pl.po file from the language-pack-pl source package).

I guess this handful of strings should be enough to investigate the problem. The next steps could now be checking if the translations are also in the installed .mo file of the binary language-pack-pl package at /usr/share/locale-langpack/pl/LC_MESSAGES/update-manager.mo. If they are, update-manager is not loading them correctly (again, due to the number of packages hitting this lately, a guess would be http://bugzilla.gnome.org/show_bug.cgi?id=574520)