The official Sacred Website has word that Sacred Underworld is gold (thanks Frans), and the expansion for their RPG should be available later this month in Germany and in other territories about a month after that:

Ascaron have announced the completion of its highly anticipated expansion pack "Sacred Underworld". The expansion pack will be available from 24th March in Germany, and from 22nd April internationally.

Players can look forward to a massive expansion containing a 40% larger gaming world, new quests, 2 stunning new characters, tons of new items, weapons, armor, and 30 new enemies.

The 2 new characters are the Daemon and the Dwarf. Both characters offer new game play features and a host of new skills and abilities. For those who have not completed the Ancaria Quest, these two characters will be provided with the level needed to head straight into the Underworld.

If you have existing characters saved from Sacred or Sacred Plus you can import these into the Underworld for a whole new Sacred experience!