Microsoft has recently upgraded Microsoft.com making it act a lot more like a desktop client. For those with Office 365 that only want to work with the web based services this is a big plus.
The new Outlook.com is more intuitive thus likely enhancing overall productivity. Further, it looks more fun in the way it operates. It can handle functions that previously was thought only could be handled by a local client.
Microsoft is rolling this out just as natural addition to the online service so there is nothing you have to do to get it other than sign up for the service. This document with embedded video provides a nice overview of what you can expect from an experience perspective when you go to work with the service.