Office 2007 Beta 2 just launched on the MSDN Office Developer Center. Check it out!
Here you will find tons of new information about Office 2007. My favorite is series of Screencasts covering "How Do I" Office 2007 development and customization topics. They are short, impactful videos that walk you through these topics:
Extending the Office 2007 UI with a Custom Ribbon
Extending the Office 2007 UI with a Custom Task Pane
Generating Office Documents using the New XML Open File Formats
Creating and Deploying a Feature for Windows SharePoint Services V3
Creating and Using Event Handlers in Windows SharePoint Services V3
Creating Custom Document Information Panels
Creating Custom Workflows with the SharePoint Designer 2007
Customizing a Windows SharePoint Services V3 site with the SharePoint Designer 2007
Getting Up and Running with Excel Services
And stay tuned... Many more are on the way!
Kudos to Erika Ehrli the Office Developer Center site manager and the MSDN team for pulling this off!
And to Ted Pattison for his excellent work in producing these screencasts.