The simple definition is that it is a kind of marriage between print and broadcast and the web. It is more of a team approach to story telling, with all journalists involved in the process of deciding in which format certain aspects of the story should be told. It involves blogging, podcasting, video, print and visual story telling, photography and much more. See the presentations below for a better picture.
The professional news scene has changed dramatically in recent years. Big media conglomerates own hundreds of stations, newspapers, radio stations, etc. They are looking for journalists who understand the big picture.
Colleges are now training students to do it all, and there is now a move in high schools to do the same.