I hadn't seen that site. Pretty much agree with the weighting though. That's from manually classifying about 1,500-2,000 tweets (so Twitter, not internet generally) as they came in which took a couple of days or so of storing them up. I bet you get that in every couple of hours now!
Yeah right now its receiving ~600 per hour, but that has jumped to several thousand when something big is going down.
Also, Twitter is definitely an (albeit skewed) representation of the internet as a whole, since the vast majority of tweets I'm seeing are linking or referring to news stories, threads in this forum, posts on Reddit, etc., from either helpful bots or users. So I see twitter as sort of a natural starting point for this type of thing.