The article on the German court decision implied that any use of a persons wireless portal made the owner liable for penalties.
A (probably) more accurate Associated Press article poste later appears to say that a suitable password at initial installation is sufficient, and it's not necessary to "take all possible measures" to prevent getting hacked.
Users can be fined if a third party takes advantage of an open connection
By Kirsten Grieshaber The Associated Press updated 9:55 a.m. CT, Wed., May 12, 2010
BERLIN - Germany's top criminal court ruled Wednesday that Internet users need to secure their private wireless connections by password to prevent unauthorized people from using their Web access to illegally download data.
Internet users can be fined up to euro100 ($126) if a third party takes advantage of their unprotected WLAN connection to illegally download music or other files, the Karlsruhe-based court said in its verdict.
"Private users are obligated to check whether their wireless connection is adequately secured to the danger of unauthorized third parties abusing it to commit copyright violation," the court said. But the court stopped short of holding the users responsible for the illegal content the third party downloads themselves.
The court also limited its decision, ruling that users could not be expected to constantly update their wireless connection's security — they are only required to protect their Internet access by setting up a password when they first install it.
The national consumer protection agency said the verdict was balanced.
[end quote - more at the link if it's still up]
Note that this did not involve "new laws," but was a court interpretation of existing law. It's still possible that there are conflicting "precedents" elsewhere in German - or other - law that could allow for differences of opinion in subsequent courtactions.