DNSSEC is a DNS superstructure and its purpose is to increase the security.
DNSSEC is a technology using electronic signature to verify data in DNS records. It means that through this verification you can detect forgery.
At the moment DNSSEC is available in testing running in .CZ domains. Soon it will be available also with other domains for those who will be interested. More details: http://www.nic.cz/dnssec/.