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Office 2010's Protected View is a sandbox that helps reduce the risk of malware propagating through emailed and web documents. It's not just for the new Office formats, either — common formats like RTF are handled the same way.
The SharePoint hosted OneNote Web App includes access to online clip art that you can use in your documents. As in the native application, you use the ribbon to open up a pop-up with the images all ready to add to your files.
At the moment the Outlook 2010 Social Connector only works with Exchange and with local SharePoint installations. However, Microsoft has announced that there will be an SDK, and you'll be able to link in to other social networks — giving you more information about your contacts.