On the back of today's Microsoft Office for iPad announcement, it's sibling app for the iPhone has gone free. When it launched you required an Office 365 subscription to use it, but as of today it's completely free for home use. Business users will still require an Office 365 subscription to create and manage documents.
Of course, it's not the same piece of software as the new iPad version, not at all. The iPad is still where the power users will want to be, but if you're a frequent Office user it's great to see Microsoft open up the iPhone app to more of us.