There was a time when Microsoft could skimp on Internet Explorer innovation. Having trounced its Netscape rival, Microsoft rested on its IE laurels for years, barely updating the browser.

Today, Microsoft can't afford to rest on any laurels, least of all with IE.
In part this is due to rising competition. The open-source Mozilla Firefox browser, for example, now tops 24 percent market share and it, along with the Google Chrome browser, and Apple's Safari browser, regularly push well beyond IE's comparatively glacial development.
However, the biggest challenge to Microsoft's IE development inertia is Microsoft itself. As Mozilla's Asa Dotzler posits:
That [IE] team has some really strong people and they're not going to let another release go by where they're still seen as badly trailing. Not with Office moving to the Web. Not with Search and other web services becoming huge revenue opportunities.
Falling short with IE 9 would be the last straw for Web developers' little remaining faith in Microsoft and so they won't miss this opportunity.
The browser used to be a sideshow to Microsoft's Windows and Office cash cows. In the future, however, the browser is the gateway to the next generation of Microsoft dominance...or irrelevance.
As the world moves online, how well Microsoft delivers an innovative browser experience will largely determine the future of the company.
At the same time, how well Mozilla delivers a neutral, innovative Firefox is the industry's best defense against Microsoft and Google too tightly coupling their browsers to their Web services.
It's therefore time for Facebook, IBM, Oracle, Salesforce, and others with a vested interest in an open gateway to an open Web to put their development resources where their mouths are. Contribute to Firefox. Microsoft (and Google) has an interest in building a better browser, yes, but to ensure that browser runs others' services as well as Microsoft's, Microsoft must be kept honest.
Firefox is the best way to accomplish this.