According to eye witness reports, the polar bear cubs (German link) born in the Nuremberg zoo a couple of weeks ago seem to have been eaten by their mother. The zoo had adopted a policy of non-interference, preferring to leave the cubs’ care to their mother. Today, she showed a first reaction, scratching at the door of her enclosure. Caretakers could not locate the cubs anywhere, their mother seemed nervous and showed no signs of hunger although it was feeding time.

I was just reading about it on BBC Online, but their story mentions two polar bears and their cubs:
New polar bear test for German zoo.

I don't know which one this was so Knut may be in danger yet of no longer being the knutest bear around.
EDIT: Update - it was Wilma.

Good and bad news
Good: Vera's baby will be brought up by hand, she could not find a secure place for it in her den.
Bad: Vera threw about seven different kinds of fits when the caretakers removed her cub.
Feelgood picture of the day

Click to view attachment

I have just died of cuteness.

Video of the baby polar bear

Another star in the making:

'Das Nürnberger Eisbär-Baby' already has her own website (at the moment only in German)