His point was that he was waiting for Facebook to make their pre-emptive response to Circles, and then FB released Groups. He knows full well is solves a different problem - that was the point of what he was saying.
Not only does Groups not really do the same things as Circles/Lists at all, but Facebook appears to think that Lists don't work. Zuckerberg:
Just take friends on a site, and cut them into subgroups. Sounds good in theory. But almost no one wants to make lists. We’ve been at this for a few years, and promoted heavily. Most we’ve gotten is 5% to make lists, and most don’t make more than one.
http://www.insidefacebook.com/2010/10/06/live-blogging-faceb...
Lists (in Facebook) suck - they UI is hidden and terrible.
Facebook Groups came out when the author expected Facebook to respond to the concepts behind Google+ Circles. It turned out that it wasn't a response to those concepts at all, and was something unrelated.
(BTW, it's not me down voting you.)
(me) nlothian @dhanji Can you settle an argument on HN? Do you know about Facebook Lists or not? http://news.ycombinator.com/item?id=2749711
@nlothian Yes, of course I do. Someone on there has already answered it: news.ycombinator.com/item?id=2749651
Agree it's not obvious for existing friends.