The SkyDrive team has announced that users can now edit documents shared via SkyDrive without the need for a Microsoft Account. This will make it easier for people using SkyDrive and sharing documents much easier as they do not need to worry about whether the person they are sharing has a Microsoft Account. Also as part of this announcement the SkyDrive Team states there are now a billion Office Documents on SkyDrive!

Read the full announcement here, http://blogs.windows.com/skydrive/b/skydrive/archive/2013/02/08/a-billion-office-documents-on-skydrive-now-with-easier-collaboration.aspx