Just this very day, a colleague suggested that the ability to "Like" an email (rather than replying to it) would save lots of time. I agreed, and speculated that it would one day happen. That day is apparently here, and Microsoft is the one making it so.
Outlook.com integrates with Facebook, LinkedIn and other social sites so that presence info, status updates, newsfeeds and the like will appear in the app in varying degrees at your discretion. You can comment, like, repost, share and retweet directly from Outlook.com -- no need to leave its warm and fuzzy confines. There's also a direct link between Facebook chat and Messenger; Skype integration is promised later.