Facebook now lets you know if your friends are using mobile app or the web

We'd hardly call it a ground-breaking feature, but it's pretty nice that Facebook now lets you know whether the friends you're chatting with are using the mobile app or the website. To the right of a user's name you'll now see the words "web" or "mobile," letting you know whether or not a buddy is seated in front of their PC and ready to chat, or out and about firing off rather brief replies. People started noticing the new feature pop up yesterday, but now the social network has confirmed that ...