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...