I imagine that one of their main target use cases is collaboratively editing slide decks, or something similar. I recall when our company had some major event last year, our exec team had over a hundred iterations of their slide deck.

edit: Their blog [1] notes that the reason is to let them focus on executing one well-defined thing WELL. Seems like a good idea.

  If we’re going to achieve these goals, we need to be 
  super focused. Which is why our first version is 
  specific in its scope: Kivo 1.0 is an Office plugin 
  which works with PowerPoint on Windows.

Kivo guys: what a great presentation, and clear explanation of what you feel is lacking in the space.

1: http://kivo.com/blog/