In a nutshell
When business decisions need the input of people in more than one functional area, cross functional teams are created. Assigning a task to a team composed of multi-disciplinary individuals from various levels in the organization increases creativity and break-through thinking.
In business today, innovation is a leading competitive advantage and cross-functional teams promote innovation through a creative collaboration process. Keeping in mind that some contributors may even be remote.
This situation requires a careful leadership balance. As such, being able to lead a cross-functional team to success requires a complex set of leadership attributes; to be a protector, a coach, an enabler and a facilitator, in essence; a truly and visibly holistic leader.