By Sarah Filman - 8 Feb 2013
...............earlier today we made it even easier for people to share and edit documents in the Office Web Apps by
not requiring them to sign in with their Microsoft account.
With an edit link, all recipients can edit your document—even at the same time. One piece of feedback we’ve consistently heard, especially from students, is that our current SkyDrive edit links can be frustrating for recipients when they find that they need to sign in or sign up for a Microsoft account just to make a quick edit to the document.
http://blogs.windows.com/skydrive/b/skydrive/archive/2013/02/08/a-billion-office-documents-on-skydrive-now-with-easier-collaboration.aspx
