The document discusses how AT&T Interactive, formerly known as Yellowpages.com, uses Ruby and Ruby on Rails extensively. It overhauled Yellowpages.com using Rails and now has one of the largest Rails sites. It discusses how Rails is used for the website tier and a Merb-based services tier. It also describes using Ruby for other projects including mobile apps and internal tools. AT&T Interactive contributes to many open source Ruby projects and conducts research on new technologies using Ruby.