A person inside a corporation who pushes for real change in terms of getting the company up to speed with technological advances, by leading an e-commerce or social media team, for example.
Almost every established company has a small team of people responsible for leading the organization onto the net. This group is often led by the company's change agent. Not many corporations like change, and more often than not, this person is seen as a threat to the existing status quo among his or her colleagues. But for companies that "get it" and need to reinvent their business to get technology to work for them, a change agent is essential. It can be a lonely job, though, one that requires all of the charm, political skills, and allies you can muster to rally your cause.