Earlier quoted context omitted.
Not really, since Tumblr doesn't have any ads either. Come to think of it, besides selling premium themes, how else does Tumblr make money? Surely all the trust-fund hipsters on the site don't bring in wheelbarrows of money with their ironic 1-gear eco-bikes, do they?
You were downvoted for adding a snidey remark to a decent question. Next time just ask the question. Since I'm curious as well, how does Tumblr make money besides themes? Does anyone know their monetization strategy?
On the Tumblr monetization front, TheStartupist[1] covers a good portion of their story. Checking Crunchbase[2] shows that they've gone through pretty large funding rounds, with their last one (D) at $30M the largest. I've been trolling Tumblr for the last year and half, and the only things I've been able to scrounge are the $9 Directory listing under your category of choice and the premium themes.
They're still growing massively, as all the cool kids congregate there to post their Instagram-faded pics of teenage angst, but are hemorrhaging money like Twitter. And like Twitter, advertising is viewed as pure evil[3] and not a viable solution to generate revenue. Twitter realized the inevitable and started Promoted Tweets recently, and Tumblr will have to do something similar soon as well. Maybe they make enough from the themes, but that seems a little quixotic.
[1]: http://thestartupist.com/2011/01/the-hypothetical-monetizati...
[2]: http://www.crunchbase.com/company/tumblr
[3]: http://latimesblogs.latimes.com/technology/2010/04/tumblr-ad...