Microsoft made a major announcement today - they will be offering “lightweight” versions of Office applications - Word, Excel, PowerPoint and OneNote - through the browser. Internet Explorer, Firefox and Safari will be supported. Users will be able to read and edit documents from the browser.

We had guessed earlier this year that Microsoft would choose the Silverlight platform to deliver Office online, but Microsoft will instead be copying the Google approach - the applications will be 100% HTML and Javascript.

This is a bold if belated move for Microsoft, which relies heavily on Office revenues and profits to support its money-burning online business.

Google, of course, has been offering online versions of Office documents since they acquired Writely in 2006. Their versions of the applications are not as feature rich as Microsoft Office, but they’re free, easy to use and allow for easy collaboration. Microsoft was forced to respond.

The pricing model hasn’t been announced yet, but Microsoft notes that consumers can currently use Office Live Workspaces for free with advertising. Businesses will likely have some form of a subscription model.

So…free Office from Microsoft, and one less desktop application. For most users this will be more than enough to make the expensive, downloaded version irrelevant. Power users who need advanced features will still buy Office, but that’s a tiny percentage of the overall market.

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