It's hard to believe that this is a headline in 2013, given IMAP has been around for decades and is extremely useful, but when the company in question is wrapped into its own email protocol, it becomes a little less surprising. Simply put: If you use Outlook.com as your email provider, you now have the option of using IMAP, a protocol that gives you (nearly) real-time access to your email in an external client - eg: Mozilla Thunderbird.
As a general rule, Microsoft doesn't recommend IMAP per se, imploring that you use its own Exchange ActiveSync protocol whenever possible. But, as many clients don't support EAS, the only option has been to use SMTP which must download each and every email in order to access them - an obvious problem if you wish to gain instant access to any email on your account, or allow a third-party to efficiently scan them.
This all said, Microsoft gives some excellent examples of what can be done with IMAP, and I'll be totally honest in saying that I had no idea some of these solutions existed. Take the mobile app TripIt, for example, which is designed to be a one-stop-shop for your trip itineraries. With IMAP, it can tap into your Outlook.com account (and Google and Yahoo! mail accounts, for what it's worth), and automatically detect updates to your itinerary and import them into the app. This means that you may not even have to refer to your email at all, but rather just this app.
motley*bunch is another app that uses IMAP in a very cool way. It's designed to help you keep track of where you spend your money online, and what you're spending your money on. With IMAP, it scans email receipts and categorizes them by vendor. It's designed to support a large variety of services, including PayPal and Amazon.
In addition to these, Microsoft gives a bunch of email management solutions at its official blog post, which I find slightly funny as some of them manage things you might imagine could be built right into Outlook itself. Nonetheless, I have used IMAP in the past and swore by it (before going Web-only), but I was oblivious to what external sources could do with it - if you're willing to pass over your email account information to third-parties, that is.