Watching the youtube video suggests LiveMatrix is more focused on letting you know about all the various live events happening on the web. That's cool too - I admit to being completely unaware of almost all such events. Perhaps there are more that would interest me.
However, I think the most interesting challenge is aggregating multiple sources covering the same event into an exhaustive, realtime resource.
Great job LiveMatrix for identifying an obvious-in-retrospect need. Let's hope they have some equally good innovation in solving the problem.