Did cnn.com really "interrupt" any "scheduled" programming with the Cuban story? They usually just have that red bar over the top with the "breaking" headline.
Obviously the definition doesn't transfer perfectly to the internet.
Traditionally breaking news is reserved for news deemed important (see previous definition). The problem is, everyone uses it too much, and if too many things are deemed important, nothing is. And we're back to where we started :).
Breaking news is a current event that broadcasters feel warrants the interruption of scheduled programming in order to report its details