The next version of Office moved a step closer to reality on Monday as Microsoft released an invitation-only technical preview of Office 2010.

However, the release of the software will be limited. Attendees of this week's Worldwide Partner Conference in New Orleans, as well as the recent TechEd show, will gain access to the desktop versions of Office 2010. Microsoft has also been taking sign-ups via its Office 2010: The Movie teaser Web site.

Also, it won't show off the program's biggest change--the addition of browser-based versions of Excel, PowerPoint, Word, and OneNote.

Those so-called Office Web Applications are being demonstrated on Monday, but the technical preview of the Web apps won't come until later this year. For consumers, Microsoft plans to make the browser-based versions a free part of Windows Live next year, but hasn't decided whether they will include advertising.

The applications, which run in Safari, Firefox, and Internet Explorer, are aimed at both expanding the number of Office users within businesses as well as holding the ground threatened by Google Docs and other Web-based productivity programs.

On the desktop side, Microsoft plans a broader beta of the software later this year, with a final release in the first half of 2010.

Much of what is in the technical preview of Office 2010 is not a shocker, given that a test version of the software leaked onto the Web earlier this year, although Microsoft is offering further details on what's in the product as well as how it plans to sell the new software.

In its last update to Office--Office 2007--Microsoft introduced entirely new XML file formats and a major shift in its interface to use a "ribbon" that shifts commands based on what the user is doing. Office 2010 is a set of less jarring changes, with Microsoft saying the goal was to make the basics better.

Office 2010 sticks with the ribbon motif, expanding it to include many of the Office components that didn't get the interface the last time around. Office 2010 will also come in both 32-bit and 64-bit versions--a first for Office.

Word gets a collection of cool image effects that stem from the DaVinci Imaging Engine that was part of Microsoft's now-discontinued Digital Image Suite product. Word, as well as the other programs, gets a new "paste preview" tool that lets users hover over different paste options and see what their paste will look like before accepting that selection.

Excel gets a new feature called Sparklines, which are tiny graphs that can fit in a single cell of a spreadsheet. PowerPoint picks up video editing features as well as the ability to create a video of one's presentation, including voice annotations.

The Outlook e-mail and calendar program adds a conversation view feature, a la Gmail. Microsoft's feature goes further though, offering an "ignore thread" option which keeps a user from having to see a message string they are no longer interested in being a part of. It also has a "MailTips" feature that offers etiquette and security alerts before doing things as replying to a large group or sending a document outside the firewall.

To handle file tasks like saving and printing across Office, Microsoft has added a "backstage view" to each of the applications. It has also made it possible for multiple people to work on the same document simultaneously through co-authoring tools.

Microsoft is also simplifying the number of different Office bundles it sells. There will be three consumer versions. Office Home and Student comes with OneNote, Word, Excel, and PowerPoint. Office Home and Business adds Outlook to the mix, while Office Professional includes all that, plus the Access database and Publisher page-layout programs.

On the business side, Microsoft Office Standard, the standard package for volume licensing customers, includes Excel, Outlook, PowerPoint, Word, OneNote, and Publisher, with the last two applications being new additions to that edition. Licensing Office Standard also gives businesses the ability to host the browser-based versions of the software. The Professional Plus version adds Access, InfoPath, SharePoint Workspace (formerly Groove), and the Microsoft Communicator instant-messaging program.

Microsoft has yet to announce pricing for any of the products.