I've been playing around with a somewhat similar project at http://news.siliconfilter.com/ for the last few weeks. My biggest challenge was the grouping that I need to do in the background so I don't show multiple versions of the same story from different sites. I'm mostly using some basic text and link analysis for that. I think Techmeme does some of that by hand.
author here: I second that - I know who wrote the widget but the developers are understandably afraid to get hacked themselves if they make their identity known.
RWW Writer here: these people are all coming to our site by searching Google for "facebook login"
Very sad, but I guess it's really a good reminder that we live in a bubble. For a lot of people, the Internet is magic and they don't know what to do when something changes.
StatCounter does get its data from sites that use their analytics package, so this is more than just a Nielsen-style prediction. I'll admit that those numbers could be skewed due to the type of sites that use StatCounter, though.
having talked to the guys on the Wave Team, it is clear that they are still trying to figure these things out. They are just now opening it up to more users and seeing usage scenarios they didn't even think of themselves. I'm guessing spam wasn't really an issue they had to deal with so far, and from what I've seen, there really is no spam on the site yet. Also, given that you invite your own contacts to join a 'wave,' chances are, spam won't be a huge problem as far as I can see.
I agree, Wave is really hard to explain, but once you see it in action, it actually becomes a lot easier to figure out.
Maybe one way to think about it as a more structured version of Etherpad, only that you can use it for collaborative editing and messaging at the same time.