Inching closer to true “software-as-a-service”, Microsoft has supposedly introduced a rental version of Office in some countries, starting with a trial based around Office 2003. For around $15 a month, someone would get the more or less full use of the Office suite. While it isn't the thin-client model that Microsoft wants everyone in the world to endorse, with massive servers in Redmond powering everything that is business, it's a step in a direction that many people would like to see. For many home users and perhaps businesses too, low rental costs based on a monthly or yearly subscription might actually end up being cheaper in the long run - assuming they always plan to continue upgrading to newer versions of the suite. After all, with licenses for Office nearing $700 for the full blown package, 3 years at $15/month doesn't sound so bad.
There isn't a whole lot of evidence of this, but it isn't surprising in the least. However, a bad mistake they might make is ditching being able to buy a license altogether in lieu of becoming a giant software rental company.