A few months back Microsoft Office 2010 Technical Preview 1 was leaked onto a the bittorrent network, but was promptly removed after Microsoft did some grumbling. Microsoft Office 2010 is expected to ship in 32 bit and 64 bit versions in the first half of 2010.
Microsoft is also expected to roll out a lighter web application version of Office 2010, together with a free ad-supported version in 2010 as well.
Microsoft is allowing registration for Office 2010 Technical Preview Program (TPP) at the following URL:

https://microsoft.crgevents.com/Office2010TheMovie/Content/Home.aspx
Registering means that Microsoft can invite you, but it doesn’t guarantee you will get an invitation.
The programs included in the preview are: Microsoft Access, Microsoft Excel, Microsoft InfoPath Designer, Microsoft InfoPath Filler, Microsoft SharePoint Designer, Microsoft OneNote, Microsoft Outlook, Microsoft Powerpoint, Microsoft Project, Microsoft Publisher, Microsoft SharePoint Workspace, Microsoft Visio, Microsoft Word, and Microsoft Office Tools.

For those that want to try out the software now, the 32-bit (x86) and 64-bit (x64) setup installer of Microsoft Office 2010 Mondo version 14.0.4302.1000 is available for free download. The leaked Office 2010 is Office 2010 Ultimate edition.
Here is the download link for Microsoft Office 2010 Mondo (Technical Preview Beta 1) v14.0.4302.1000:
Torrent (32bit and 64bit): MICROSOFT.OFFICE.2010.v14.0.4302.1000.BETA.1.VOLUME.X86-64.ENGLISH-WZT.torrent
The torrent above will download both 14.0.4302.1000_Mondo_volume_ship_x86_en-us_wzt.rar and 14.0.4302.1000_Mondo_volume_ship_x64_en-us_wzt.rar.
Below are the download links for the setup installer via HTTP:
HTTP (x86 32-bit): 14.0.4302.1000_Mondo_volume_ship_x86_en-us_wzt.rarHTTP (x64 64-bit): 14.0.4302.1000_Mondo_volume_ship_x64_en-us_wzt.rar
Keep in mind when trying out this software that it is still full of bugs.
Below are some preview shots of Microsoft Office programs that come in the preview:

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