Over the weekend C|Net ran a story indicating the Mozilla Foundation hopes to add calendaring functions to its Thunderbird e-mail client (right), turning an open source Outlook Express clone into something more like Microsoft Outlook.

What follows is pure speculation, but this could make Firefox the big story of 2005, and beyond.

What would it mean to have a version of Outlook that was not only free, but open source?

For one thing, it would mean you could create applications that integrate that calendar functionality with other things, without first asking Microsoft's permission.

For instance, you could integrate calendaring and e-mail functionality into a system you could access with a cell phone. Then you might integrate that calendar with, say, GPS and mapping data.

Suddenly you have an enterprise application that can keep your mobile staff up-to-date, and give them the directions they need to stay on top of business.

And, of course, you can also now build applications on browsers and basic e-mail functions without going "mother may I" with Microsoft. You simply "fork" from Thunderbird or Firefox, maintaining your own copy of the code base and hosting the additions on the same open source basis.

All this unleashes the true power of open source on common applications for the first time. Because open source lets you see the innards of the application, and the open source community can help you with your development questions, we can actually build on these applications for the first time, in many different directions, without waiting for someone else to make a business case to Redmond.

And if basic applications that run under Windows are more powerful and extensible when they're open source, what about the operating system itself?

Thus do monopolies fall.