A Chief Technology Officer could be said to have a bias to working "IN" the team rather than "ON" the team.
He/She might have a bias to look "IN" rather than "OUT" from the IT/Tech Team.
He/She should be passionate about existing and emerging technologies and how they can be used to create competitive advantage for their company.
He/She might read Hacker News, Slashdot, have and use a GitHub account.
A good CTO will have kept their core technical skills up-to-date. They won’t have the time or experience to do every person’s job in their team but they will have maintained a core set of technical skills that are up-to-date and relevant.
He/She might have come up through the more "technical" routes of Architect, Development Manager, Developer etc.
He/she Is also normally the lead technology evangelist and advocate in the company.