Microsoft's cloud storage service SkyDrive has hit a significant numerical landmark: over a billion Office documents are now hosted on it. To celebrate, Redmond has made is a little easier to edit files using Office Web Apps -- you no longer need to sign in using a Microsoft account (unless the sharing party wants you to), so if you've got the right link, you can start tweaking with minimal fuss. A billion Office files sounds like a big number, but we'd really like the details of how many users that's spread over. As many as DropBox? Who knows.