Google has removed over 11 million .co.cc sites from there search engine because they saw the websites as being too "Spamy".

According to According to Matt Cutts, head of Google's web spam team, the firm has been classified as a "freehost", and is not authorised second-level domain like ".co.uk".

(source)

We absolutely do try to be granular, but I wanted to mention that if we see a very large fraction of sites on a specific freehost be spammy or low-quality, we do reserve the right to take action on the freehost as a whole.

-- Matt Cutts

Oliver Fisher, a member of the Google Anti-Malware Team, wrote a post on the search engine's Online Security Blog to explain the massive take-down.

(source)

Over the past few months, Google’s systems have detected a number of bulk subdomain providers becoming targets of abuse by malware distributors. Bulk subdomain providers register a domain name, like example.com, and then sell subdomains of this domain name, like subdomain.example.com. Subdomains are often registered by the thousands at one time and are used to distribute malware and fake anti-virus products on the web. In some cases our malware scanners have found more than 50, 000 malware domains from a single bulk provider.
Google’s automated malware scanning systems detect sites that distribute malware. To help protect users we recently modified those systems to identify bulk subdomain services which are being abused. In some severe cases our systems may now flag the whole bulk domain.

-- Oliver Fisher

The .cc top-level is owned independently by a Korean company situated in the Cocos (Keeling) Islands, a small Australian territory in the Indian Ocean. Regular .cc websites are unaffected by Google's changes.