Hi PLD,
I do not know the exact hiring number, but what you can learn from their pages is that they are going to hire 1000 new people for 2012 in general. There are two assessment days I know about (9.2. and 16.2.2012). I will attend the first one so wish me luck!!! Got the call three weeks ago.
If you have any questions do not hesitate to send me a PM