Rumors concerning a mobile version of MS Office have been circulating for over a year. I had not been taking them seriously, but today it looks like I might be wrong.
The Verge is reporting that they have multiple sources which have told them that Microsoft will be releasing Office for Android and iOS next year. They cannot offer a firm release date, but all signs point to a release in the first half of the year, with March as the most likely month for the release.
The iOS apps will come first, with the Android version of the apps reportedly coming in May. The apps will be free to download, but if you want to do more than simply view Excel, Word, and other Office files you will need to buy a copy of Office 365.