Microsoft delivers a partial preview of its Office Web Apps

When it released a technical preview of Office 2010 several months ago, Microsoft promised a companion suite of web-based Office applications. Today, the company released a partial preview of that package to a limited set of beta testers and invited guests. I saw a preview of the Microsoft Office Web Apps package last week and learned some details about what it will and won’t do.

Officially, Microsoft is positioning the new web-based offering as “online extensions to Word, Excel, PowerPoint, and OneNote.” In this technical preview release, there are still some rough edges and missing pieces. Specifically:

• Testers will be able to create and edit files using Excel and PowerPoint.
• Word files can be viewed but not edited, and OneNote won’t be available at all until launch.
• The Backstage feature, which consolidates information about files and options in a single page, won’t allow opening or saving documents to the web in the tech preview.
• You will not able to publish to a blog or a website in the technical preview, although this feature will be turned on in the final edition.

In the demo I saw, Microsoft took great pains to emphasize browser compatibility, opening and editing Excel and PowerPoint files using the latest version of Firefox on Windows and promising the same degree of compatibility with Safari 4 on OS X. Retail customers can access the suite via the free, ad-supported Office Live service, which includes 25GB of SkyDrive storage. Corporate customers will be able to install and run the service on their own SharePoint servers or as part of a fee-based hosted SharePoint offering.

And although the new web apps are scheduled to launch around the same time as Office 2010, that’s not a hard link. Users will be able to upload, edit, and share files created using Office 2000 and later versions on PCs and Macs.

The big question, of course, is whether this offering will cannibalize sales of the desktop versions of Office or whether they’ll act as companions and discourage customers from jumping ship to other online solutions. The demos I saw were faithful to the Office look and feel, but I won’t be able to judge their actual features and capabilities until I can try the web apps for myself. When I asked a Microsoft spokesperson this question, I got a predictable response: “These streamlined online versions can do a lot, but the power of the two [web apps and desktop apps] together is important. I'm not going to want to write a term paper or build a PowerPoint presentation on the web-based apps.”

I’ll have a closer look at Office Web Apps next week, after my account goes live and I've had a chance to work with it.

[See also: Microsoft Office Web Apps go to testers: Ten things to know by Mary Jo Foley]