From the RegUk:
Spanish Web site operators have taken their sites offline in protest at government proposals to regulate online content.
The spontaneous protest comes amidst deep concern among free speech advocates about Spain's "Law of Information Society Services and Electronic Commerce" (or LSSI as it is known in Spain), which became effective on Saturday (October 12th).
Under the law Web sites must register with the government and ISPs are obliged to monitor sites for illicit content, which they must report to the authorities.
Failure to comply with the law would result in heavy fines of up to â‚¬600,000.
Ahh... free societies. Don't you love 'em?