I think you'll find it's because they are rolling out Windows Live SkyDrive:
Windows Live SkyDrive makes it easier than ever to access your
files wherever and whenever you need them. Now get a huge
5GB of FREE online storage to securely store and share your files.
All you need is your Windows Live ID.
> 5GB of free online storage in private, shared or public folders
> Password protected and always available when you need it
Which comes live today, at least thats what my guy at MS Reading has told me.