I like #3 (Score 1)

There is power in being ubiquitous. Office needs to be supported, at least in some capacity, on all desktops. I highly doubt that they are doing a full port, since it is so heavily integrated into the operating system (Office really is a full development suite, with support for third-party activex components and other add-ons- too much would have to be ported). I wouldn't be surprised, however, to see some sort of subset of Office get ported- at least document viewers for all types of office formats, and some of the base functionality that is required by 90% of users. This allows them to keep comptetition such as Corel from gaining inroads due to their support for Linux.