For adult webmasters and bloggers, the real ruckus started when Tumblr prepared itself for a Yahoo buy-out by appearing to purge itself of adult content. The micro-blogging site did this quite effectively when it dealt a dirty blow to Tumblr users by using robots.txt to exclude the search engines from indexing sites labeled as “adult”. This was reported in accurate detail by Bacchus at the long-respected ErosBlog. (it must be noted that Tumblr does not seem to be using the Robots Meta Tag. Do you know about robots.txt files and Robots Meta Tags?)
This was reported by Bacchus before anyone even had an idea that Yahoo & Tumblr were in talks. Just days later, Bacchus again discussed issues for adult bloggers at Tumblr, i.e. how difficult it became to even search your own Tumblr blog & how to back-up your Tumblr site. By this time, the rumors had become official news: Yahoo had purchased Tumblr.
Via Gracie Passette