Tumblr is an impressionistic blog, often very visual in its nature. Tumblrs are easy to form and start; compose a name, grab a theme from many offered, and start posting. Tumblrs are often composed of the gleaned posts and pieces of other Tumblrs. There are now thousands of Tumblrs and they've become addictive to some - both posting and reading. The infrastructure is analogous to platform-as-a-service, as Tumblr provides much of the support needed for many kinds of media types, and is simpler to use than even WordPress, in my opinion.
Tumblrs also have great popularity because as far as I can tell, there is no censorship of any kind. You can have beyond MySpace-like boldness, or Spartan simplicity. It's your choice of theme, and your skills at doctoring your pages after having chosen a theme. Some Tumblrs are beautiful while other pages are strictly porn, and some are actually pretty disturbing stuff. Porn often dominates the images, but math porn as well as sex porn.
There are confessionals, the studies in visual narcissisms, the serious geeks, and not a lot of MySpace-like youthful rebellion. It's gay, straight, undecided, and it's a big problem: part of the culture of Tumblr is to move graphic objects into your own Tumblr. Tumblr, like no other site I've seen, tests the Fair Use strictures of copyright law. It's a minefield where the culture is to post because it makes your Tumblr more interesting.
Wholesale copyright questions don't include music sharing that I've found, although I'm surprised that there aren't more YouTube-like DCMA takedowns. It's that part of the rawness of Tumblrs that make them more attractive to some. They're in your face, but then they're subtle. Tags are big, as are long lists of followers. Followers imply leaders, and I'll imagine that there's a way to create a taxonomy of thought-segment leadership easily. Every post leaves a trail, if not of the origin of the bits of the post, a list of people that admired it, commented on it, or stole - I mean reposted it.
Therein lies the impact of Tumblr, as it embodies the "new new" values of the web - strong sharing where reposting and amalgamation creates new objects - and potentially runs slipshod over the concept of ownership. The collaborative results can be startling. They can also pander towards the very basal in onerous ways. The temptation to share many objects within Tumblr is high because sharing is comparatively easy to other "micro-blogging" platforms and easily approachable by civilians. An increasing number of apps exist to make the job of linking and sharing more simple.
Last week, it was reported that Tumblr was close to getting between $75 and $100 in venture capital. Tumblr's revenue models could be large, and for several reasons. Currently, only savvy users have the ability to add widgets that earn them advertising revenue, usually through http_referrer clicks. Some of them lead people into the highly evolved world of porn payments. Tumblr has the possibility of allowing users to put advertising areas inside the themes associated with Tumblr, and the tracking used by Tumblr puts it in league with the data assembled by Google.
The bottom line is that Tumblr leaps over other blogging platforms, but there is a risk of being associated with the more disturbing warrens of Tumblr, and being caught up in a maelstrom of copyright issues that are unsolvable in some cases. Still, Tumblr has many of the compelling elements that made the web popular: enthusiasm, sharing, visuals, and emoting ... and strong dashes of sex.