Tumblr recently launched a new tool to help discover content beyond following other users. Basically, it's aggregated feeds of certain hashtags as curated by some vetted Tumblr users. Here's the background info but, really, you should just dive right in to the News Topic and see what it's all about. Given that these four Tumblr users are the current curators (plus Mark Coatney) I'd say it is in good hands. Looking forward to the new stream of content.