I'm not exactly sure why the two would be compared. Isn't that like comparing the number of Worlds of Warcraft players to the number of Microsoft Word users? I understand that they're trying to make the point that StumbleUpon should be getting more press because it's bigger, but, honestly, there's only so much one can write about it. It's a nice little utility to help people discover content, but it's not disruptive by any means whereas Twitter is actually changing the way people, governments, journalists, politicians, and corporations do things.
Because they are both startups and they both get coverage from the same tech news media. Which makes the inequality of coverage relevant given the amount of users.
Let me give an example to try to explain it better.
People always complain that Celebrities like Lindsay Lohan get far too much coverage by the mainstream media while important Government issues like the Stimulus package get too little coverage. The media's excuse is always "we're delivering what the public wants to hear." But if someone could somehow prove the public wants to hear about the stimulus package more than Lindsay Lohan it would make for a great counter argument against that menatality.
That's what this comparision is (with Twitter being Lindsay Lohan and StumbleUpon being the Stimulus Pacakge)
I've always liked StumbleUpon and, with no offense to Twitter, I think the concept is far more innovative. More importantly I think it does a lot more to make it's users smarter. So I'm always annoys when Twitter gets so much digital ink while StumbleUpon gets almost none.
