Those of you that are Outlook.com users probably know that Microsoft hasn't really changed the UI since it launched. There have been some changes, like integration of Skype, new filters system that have happened, but nothing significant to the way your inbox looks.
Today, I have noticed a change! In the bottom of the left pane, under the folders there is a messaging box (that can be minimized). Clicking on a contact opens the messaging pane on the right, which appears to be the same.
I don't know why they put that there, when there was already a pane on the right for it. However, a box with all (or some?) of your contacts showing could be useful. Also, it is perhaps notable that this is similar to where the Gmail hangouts/talk is located (although in the rumored redesign it is moved to a pane on the right).
As a bonus I also noticed, in the upper right corner and to the left of where it has your account settings, to be an undo arrow. It is blurred in my picture, but your Outlook.com should have it (confirm or deny in the comments). One of the useful features that a popup informed me was that you can use Ctrl + Z to undo, in addition to clicking the arrow (which I have confirmed works).
There was nothing official from Microsoft when I wrote this (apart from it also showing up in recent Outlook.com YouTube clips that I overlooked until now), so I can't tell you anymore. Have you guys noticed/received these changes? Do you like them?