Read on for some ideas about the rankings, and where RSS aggregators are going.
The interesting part comes in the top contenders. The web-based Bloglines is #1 by a long shot. This is, I believe, because of two factors. The first is the "no install" factor. Why not setup a Bloglines account? Just go to a website, register, start reading feeds. And access your news from work, home, or anywhere with a browser. No installing, no selecting an app, no paying or demo apps.
This goes nicely with my ideas around RIAs. Actually, Bloglines isn't very "rich" (yet!), but it is a well-put together web app.
The second factor is what I'll call the "newbie factor". Any sort of guide to blogging/RSS reading typically includes a link to both Bloglines and MyYahoo as two easy ways to start reading feeds. And because of the no-install factor, lots of people do create accounts. Heck, I still have an account -- so those numbers might be skewed the same way "abandoned" blogs are: how many of those subscriptions are for active accounts? A "What if someone subscribes to your feed but doesn't read it?" sort of thing.
The second highest aggregator (although half that of Bloglines -- 32% vs. 16%), is NetNewsWire. A Mac-only app. Let me say it again: Mac only. So that means that of all of the people aggregating RSS feeds, a heck of a lot of them are using Macs.
I have a couple of theories here. First is lack of insanely great news aggregator for Windows. NewsGator seems well-liked, and probably fits well in the using-at-work crowd. But there are lots of people that don't like to treat RSS like email, and also lots that don't like Outlook. FeedDemon has been recommended to me as a good option, but it is for-pay only (NNW has a "Light" sibling that is free).
So, is great news aggregation software driving people to the Mac platform? I wouldn't stretch that far.
I guess my second theory must be true: of the power Internet users that use RSS, many of them (a majority?) use Macs. This also suggests to me we're not even close to seeing mass market adoption of RSS. I mean, I knew that, but these numbers seem to clearly indicate that.
What happens when the masses arrive? Well, I happen to think that the masses aren't interested in news aggregation. They don't want to drink from a firehose of 100, 200, or (Roland, Scoble) 1000 feeds. They want news they're interested in (topics + filters) and they want to be kept up to date with "stuff" (i.e. notified - searches, PubSub, etc.).
This will in part be satisfied by portals. Only Yahoo fits here -- Bloglines needs to get less aggregator-y and more custom-web-page-y; yes, kind of like Kinja, but with (still) less focus on this thing called a "weblog" and more of a focus on stuff-I-want-to-know.
The other half of this "stuff comes to me" will be handled by desktop apps. But not general news aggregators (although some of them might evolve to do more than one thing). You'll have your music app thingie -- powered by RSS (think audioscrobbler, last.fm, and, heck, "podcasts" directly into iTunes of new music). You'll have your photo thingie (it's here, it's called 1001). And your average end user won't know or care that RSS is a standard for pushing content around the Internet.
What else? Well, Marc's OpenListings will want a dedicated classifieds app. Well, maybe more than one -- one for buying and selling general stuff (like your newspaper or craig's list) and perhaps another, fancier one for looking at real estate.
These custom, single purpose RSS apps? They'll be cross platform. They won't be installed. They'll have a web component that they tie into. They might look a bit like Gush.
I'm looking forward to it.