[UPDATED 5/8/09]

We’ve looked at the similarities and differences between Tumblr and Twitter before, but Tumblr’s latest new feature buts adds interesting twist to the comparison. Today, by way of the staff’s own Tumblr, a new Activity Page (below) and the concept of “tumblarity” were introduced:

“Tumblarity” is a bit difficult to appreciate without knowing how Tumblr itself is structured. Tumblr is a (and at this point sort of the) micro-blogging platform. Users post different types of content—typical text posts, photos, videos, audio clips, links, quotes—to a publicly viewable page (their own Tumblr) that they can style and customize much like a traditional blog. Not much surprising there. But Tumbr isn’t only or even mainy a persona publishing tool. The Tumblr dashboard from which users post new content also displays the most recent new posts by everyone on the network that each user has chosen to “follow”. The dashboard allows labeling a post as something one “likes” (it gets a little heart next to it) and reblogging a post from someone else on ones follows onto one’s own Tumblr, sometimes with their own comment tacked on (subsequent reblogging allows this serve as a sort of threaded conversation). Overlapping and intersecting networks of mutual followers create, share, “like” (in a way that demonstrates affinity with an icon, not just private appreciation), comment on and even (in a sense, by was of reblogging) collaborate on content. It takes the following structure made most famous by Twitter and applies it to material that greatly exceeded Twitter’s 140 character limit.

But the the (somewhat) more substantial nature of typical Tumblr content—its weightiness, at least compared to that litte blue bird—means it’s really not geared towards following hundreds or thousands of people, more like dozens.

But those it’s that possibility of having followers in the six or, recently, seven figure range that has gotten Twitter a lot of its recent attention. Ashton Kutcher and CNN racing to one million followers (as was the case on Twitter a few weeks ago) isn’t the sort thing that Tumblr seems likely to produce. That in itself probably isn’t a huge problem, but it points to something that might be. Racking up Twitter followers is an easy game to start playing. The structure of and culture around the service lends itself to the idea that that’s what people should want to do. It’s not that people on Tumblr don’t want attention—everyone on the Web wants attention. Rather, Tumblr’s feature set and the way its community is structured don’t lend themselves quite as easiy to evaluation and comparison.

Tumblr confronted this head-on. They’ve revealed to the word the metric they use for ranking different Tumblrs in search results and for their “popular” page. Everyone can now check to see exactly where they fall in the hierarchy of “tumblarity”.

Accumulating followers on Twitter or freinds on Facebook is easily characterized as pretty empty pursuit. But tumblarity isn’t just about how many people follow you. It’s about how often they “like” what you post. It’s about how often they rebolg what you post and how often it gets reblogged from them. It’s about how frequently you post. In other words, it’s about how much value you are adding to the network as a whole.

As a result, trying to achieve a higher level of tumblarity is in large part about producing better and more interesting material. And the higher your tumblarity, the higher the chance that other users will encounter your content through searching the site or the “popular” and, if you’re lucky, maybe their attention will push you higher still.

Is this starting to sound familiar? If you’ve ever worried about search engine optimization or bothered to find out what happened to Ata Vista, it should. What Tumblr is doing resembles one of the most important and infuential ways the Web gets organized: Google PageRank.

A site’s PageRank is a value between 0 and 10 that Google assigns based on the extrent to which other sites link to it. Google uses this metric to determine what the Web as a community thinks is most important PageRank isn’t the entirety of Google Search, but the core insight is important and was a big factor in setting Google apart from its competitors back when it was still sort of a contest. Significantly, a site’s PageRank is public knowledge. Tublarity isn’t fully public (yet) but it’s also an evaluation that’s transparent to the evaluated. You’re still told where you fall and the criteria for improvement are clear.

That alone is probably enough to get a certain sort of person competing and a cynic might say that’s all Tumblr is trying to do. But there’s something more interesting about Tumblarity. It means more than just raw number of followers (or in the Google analogy, traffic). It has to do with the quality of content and how a broader community responds to it. The ranking might easily become a point of pride and in that sense it is like the number of followers on Twitter. Plenty of people want their sites to score higher on Google as well but that’s rarely a matter of social interaction; it’s usually business.

Tumblr is bringing these diverget sensibilities of these two hierarchies together in a social web environment. Look at the Activity Page. It looks a whole lot more like a Google Analytics screen than it does a Twitter feed or a Facebook profile. I’m not saying that Tumblr is more serious than Twitter and Facebook, but it might be less frivilous. The next question is whether tumblarity, to the extent it catches on, enhances that quality of the service or deminishes it.

And to return to the Google analogy, that questions enourmously larger version: does the PageRank concept enhance or deminish the positive qualities of the Web as a whole?

I think in both cases a big part of the answer turns on how well these types of ranking can be designed to avoid exploitation—”artificial” attempts to gain points that avoid the intended requirement of creating something others find worthwhile.