The office suite software market
There once was a time, when Microsoft Office was "just another" office suite. Back then, WordPerfect was the preferred wordprocessing application in the USA, while Microsoft Word was a best seller in Europe. Microsoft has won that war. Illegally (proven guilty in court in the USA).
Either way: Today, there are two main competitors for the whole office suite market: Microsoft Office and OpenOffice.org. OOo tries to look, feel and work as closely to MS Office as possible. It's MS' task to find ever new ways to do the same things all over again, because if people stop upgrading to their new versions, they lose.
Now: Apple has started to re-enter the market with iWork. (Apple clearly has abandoned AppleWorks back when OS X was released in 2001.) Slowly, they're trying to do things differently. There's no real sense in directly competing with MS Office and OOo - Apple has acknowledged that. The question for me, however, is: Will Microsoft be able to fight off OOo in the long term?
On the Mac platform, it seems like OOo doesn't get off the ground. NeoOffice/J (a Java implementation of OOo for Mac OS X) is nice, but slow and doesn't feel like a Mac application. OOo itself on Mac OS X is even worse, uses X11 as the interface, which never feels just like a Mac application.
On the PC side of things however (Linux and Windows), OOo does well, and it keeps getting momentum. In my opinion, the innovation in office applications is done. OOo does basically everything it needs to do, and does them well enough. From 2.0 on onwards, OOo will have the task to defeat MS Office. It doesn't look too well for MS right now, although their defeat will take time.
On the Mac side, Apple will try and be there, should MS ever decide to kill Office for the Mac. And OOo takes its time, but will
one day come to the Mac for real, too. At least we Mac users aren't in the position where we have to actually fear
MS leaving our platform. Mac OS X has grown up. The applications are here. With or without Microsoft.