If you were to ask people in the street about Tumblr and what it was for, I would be surprised if you had many people say 'porn!'. They might not have heard of it or they might remember it from a decade ago or they might even think it was 'flickr'. It certainly is not up there with Twitter and Facebook as a full on household name.

The next 'tumblr' that comes along, i.e. when it is another thing that Automattic do, need not carry over any of the adult content connotations of the past. It can be fully repurposed with the SFW punters happy with whatever comes next. I doubt it will be mySpaced.