There are already lots of hashtags on Facebook, either through people cross-posting updates from Twitter or Instagram, or simply carrying the habit across their social networking activities. Now it seems Facebook may be planning a more #formal #adoption #of #the #hashtag. The Wall Street Journal reports that Facebook is working on allowing its users “to click on a hashtag to pull up all posts about similar topics or events so it can quickly index conversations around trending topics and build those conversations up, giving users more reason to stay logged in and see more ads”. That sets out the reasoning neatly: hashtags may be beneficial for users, but if Facebook implements them it’ll be as much about its battle with Twitter for social media advertising budgets, including mobile. With Twitter hashtags increasingly prominent in offline marketing – TV and billboards for example – it’s not a huge surprise that Facebook wants in on the action.