One of just about everyone's predictions for 2007, mine included, is that RSS will take off next year.  As several people have pointed out, this has been said before.

So what makes 2007 any different?

1. Well for one thing, I think one of the major developments we saw in 2006 was the mass entrance of the general public into the social networking space via MySpace.  The average person is now familiar with creating content and consuming content created by OTHER people they know.  Realizing that there's content out there that you're interested in is the first step toward understanding what RSS is for.  Prior to 2006, the average person only used the Internet for email, paying bills, reading news, and searching for stuff.
2. Customizable home pages.  Gone are the days of the static MSN or AOL.COM homepage.  Now the average user is practically begged to add dynamic content to their home page.  When you look at your Google or Microsoft homepage now, it's pretty hard to miss the big "Add stuff" link, which is an obvious segue to RSS consumption.
3. Another key driver is going to be all of the alternative uses for RSS that are starting to pop up everywhere.  Even if they're not interested in keeping up with a blog feed, they're bound to be interested in one of the many other information sources now available as RSS.  They'll need to find something interesting to put on their homepage, after all.  And once somebody uses RSS for one purpose, it's not hard to transfer that knowledge to another use.
4. Finally, the toppling of MySpace as the dominant social network is going to play a key role.  MySpace is notorious for holding user data hostage and exploiting their users for a quick buck.  Hell, when somebody sends you a message on the thing you get an email telling you that somebody sent you a message and you should go log in to check it.  Gotta rack up those ad impressions, I guess.  But in any case once a more user-friendly and open social network becomes the cool place to hang out, a social network that sees the benefit in allowing users to syndicate the content they create, RSS is going to be front and center.  I think this will be the key moment when RSS finally penetrates the public psyche.

So there you go, those are the reasons "RSS will go mainstream" made it into my list of 2007 predictions.  Obviously there are a few dominoes that need to fall first, but I don't think any of them are very unlikely at this point.