Notwithstanding the fact it will be many years before very many corporate users might be able to work in a "Microsoft-free" environment, there appears to be significant effort being put forth to make it a reality. From the geekiest tech pubs, like the Java Developer's Journal to august ones such as The Wall Street Journal, circumventing Microsoft is a hot topic.
I choose "circumvention" deliberately, as many of the strategies intend not so much to eliminate Microsoft from the equation but to limit our dependence on Microsoft and limit the payments users make to same.
The rise of the browser as the ubiquitous client portal has already loosened Microsoft's grip on the desktop. After all, if I use applications like Salesforce.com (and myriad others) that are built with the browser, I can get my job done from any browser-enabled computer - which is to say any computer.
Microsoft has devoted massive amounts of effort into making .Net into a top-notch development framework (and, I think succeeding in that effort.) Also, the Mono project was formed to allow developers of .Net applications to be able to run on non-Windows platforms (because Microsoft only provides a Windows run time). If Mono achieves its goals it will let developers leverage Microsoft efforts while ultimately circumventing Microsoft.
Finally, in the bowels of geekdom, you'll find the Apache Jakarta POI project, the goal of which is to circumvent (again) Microsoft by providing an API that lets Java programs access Microsoft Office file formats.