For the records...
I've just returned from Germany.
Got there last friday, bought an Aldi-Talk GSM card. It didn't work but I was busy through the day and only at night realized I had to fax-in a registration form.
Sent the form on saturday early morning.
By Tue evening when I boarded back to my country the card was still not working. Monday was a holiday which would explain a part of the problem, but the fact is that for me that card was EUR 15 thrown in the trash bin...
Gustavo