Tumblr has announced that there are now premium themes available for Tumblr. Premium meaning that they cost money and are generally much more refined then the over 350 free themes already available for Tumblr.
Two things: First, I love that Tumblr is doing things to monetize their platform for both themselves and their design-savvy community. Any service that you love should, at some point, begin to monetize. If they don't, they won't survive. These types of moves by Tumblr are moves that will ensure their longevity as a service. Second, I think some of the free themes could easily be pulled into the Premium themes category and the designers of which could make a few dollars on them (since this model wasn't available when they originally designed their free Tumblr themes). I wonder if Tumblr reached out to some of them?