We never thought we'll live long enough to see this day. Microsoft is reportedly working on a release of Office for Linux and looking at a release date as early as next year.
According to a report over at Phoronix, the information was revealed during the Free Open-Source Developers' European Meeting held the previous weekend at Brussels in Belgium. It was also revealed that this will be a fully native Linux port of the application, and not dependent on Wine or similar compatibility layers that let Windows applications run on Linux.
From a source in Brussels, Belgium during the Free Open-Source Developers' European Meeting (FOSDEM) this past weekend, I was informed that Microsoft is having a "meaningful look" at a full Linux port of Office thanks to Linux showing signs of commercial viability on the desktop. Right now some versions of Microsoft Office will work under Linux via the use of Wine or CodeWeavers' CrossOver to varying extents, but this port being evaluated internally at Microsoft is a fully native implementation. Evidently there's already some port to unknown completion that has been done internally at the company.