As the .CO launch has been completed, the major Internet search engines and portals have all adopted this new opportunity.
Twitter has registered T.CO with the specific purpose of using it for their Link Service. A message on www.t.co reads: “Twitter uses the t.co domain as part of a service to protect users from harmful activity, to provide value for the developer ecosystem, and as a quality signal for surfacing relevant, interesting tweets.”
Google has registered google.co, youtube.co & adwords.co
Yahoo has registered yahoo.co
facebook.co is a reserved name