As someone who both leads virtual teams and trains leaders in communication, I have two primary, interlocking strategies for keeping the team engaged and aligned.
First, develop a personal relationship between every member of the team. Ideally, this is through an initial face-to-face meeting where very specific attention is given to building interpersonal connections between team members. Where this is not possible, arrange Skype (or equivalent) introductory conversations between each member pair so that they can develop a personal relationship, learn about each other as individuals, with families, interests, etc, as well as their work roles.
Second, start every virtual meeting, whether by phone or videoconference (preferable), with a check in where each person gets a minute (or more) to name their successes, in any aspect of their life and work, since the last meeting, plus any personal or professional challenges they have faced. This is essential to engaging team members in each other's lives and work, to ground the team in the real people who are there, and establish the context each is coming from. Meetings begun this way are far more likely to be closely attended to (fewer disruptive multitasking behaviors) and are apt to be more cooperatively productive because team members are reconnected to each other at a personal level-- committed to each other's success.