The just-released Technical Preview of Office Web Apps is a still-incomplete piece of work that points the way towards Microsoft's vision of integrating Web-based and client-based versions of Microsoft Office.
When it launches next year, Office Web Apps will consist of four applications: Excel, PowerPoint, Word and OneNote. In the Technical Preview, many features are missing from the apps, and some are more fully developed than others. For example, in Word you can only view documents, while in Excel you can create spreadsheets, edit them and collaborate with other users. OneNote isn't available at all yet.
Even at launch there will still be some features missing. For example, only Excel and OneNote will allow co-authoring (letting multiple people collaborate on a document simultaneously). Neither Word nor PowerPoint will have those features at launch, although Microsoft says they will be added in the future.
Office Web Apps works on Internet Explorer (version 7 and later), as well as on Safari (version 4 and later) and Firefox (version 3.5 and later). Chrome is not supported. There was only one exception to this rule: If you're working on a document on Office Web Apps on your PC, and want to open that document locally in Microsoft Office on your PC, you'll need IE7 or later.
I used it on Windows, Mac and Linux platforms, and it worked the same on all three. You'll also need Microsoft Office 2003, 2007 or 2010 (also in Technical Preview) on your PC. On the Mac, you'll need Office 2008 or greater.
Understanding the different versions
Just as there are different versions of Microsoft Office, there will be different versions of Office Web Apps:
* The consumer version, which is what I tested, will be free, although "free" will come at a price when it comes to the user experience, because it will include advertisements. There are no ads yet, and so no way to know whether they will be disruptive or barely noticeable. As of now, Microsoft has no plans for releasing a for-pay consumer version of Office Web Apps that will allow you to dispense with the ads.
The consumer version is tied to Microsoft SkyDrive, Microsoft's free online storage service. That's where you'll store, create, edit and share your Office Web Apps documents. The service lets you designate certain folders as private and others as shareable with people you specify or with anyone.
* The hosted version will be available to business customers who pay for hosted accounts on Microsoft Online Services, which is powered by SharePoint. No ads will be in the interface.
* The corporate, in-house version is for enterprises with volume licenses for Microsoft Office and a SharePoint server. In this version, enterprises will host Office Web Apps on their own SharePoint server. No ads will be in the interface. Enterprises will not have to pay extra for this; it will be part of the volume license for Microsoft Office.
Most of the features of these three versions will be identical, although there will be some minor differences. Besides ads, the consumer version will include a feature that allows publishing to third-party blogs, Web sites and wikis, something that the other two versions won't allow. The other versions, though, will track document lifecycles, allow for backup and restore, and give IT staff control over how the application is deployed and used.
Your Office home in the cloud
Office Web Apps uses Microsoft's Windows Live SkyDrive online service as its home base. In order to use Web Office Apps, you navigate to a special area of SkyDrive, where you get 25 GB of free storage space.
From here, you can go to a My Documents page where you can create new Office documents, upload files, create folders, and manage sharing and permissions.
Click any document, and you'll see a screen that shows basic information about the document, including file size, the date it was created or uploaded, the last date it was worked on and so on. The page also lets people make comments about the document. You can view the document, edit it, download it to your computer, move it to a different folder, copy it and rename it.
Once you start using it, Office Web Apps looks and feels much like the client-based version of Office; in fact, it looks more like a polished client application than a Web-based one. It displays Office documents in full fidelity so that they look exactly the same way online as they do on your PC.