My first instinct here would be to implement this not like tumblr reblogs but more of a "share with your circle" feature. This would make the post show up on your followers' reading page if they have access to it, but not create a copy or allow separate commenting. It keeps the interaction in the sphere of the original poster but enables easier, more free-flowing curation of other posts. Of course it's possible today to have a journal that just links to other posts, it's just a way more complex workflow that doesn't work well for mobile users. Being able to curate a feed of other pests might also serve some of the desire for globally searchable tags, or if globally searchable tags are also implemented, give users tools to manage that flood and reduce wank potential.