If you are a Microsoft Hotmail user, then you will be seeing solicitations in your Inbox to upgrade to "Outlook.Com". Basically, this is a new interface that streamlines some services, for example, SkyDrive, Calendar, Skype (coming soon). But really it is a harbinger of things to come or things that are already here: Windows 8.
If you have used Windows 8, as I have, then you will notice that Microsoft is merging the Metro styled interface across the board: on tablets, on PCs, on laptops, on phones, and ...online.
Go directly to Microsoft's Outlook site for any questions