The Office 12 system release has been formally named "Office 2007" by Microsoft. I'm running Beta 1 software and it's quite interesting and looks like some great changes. The new Outlook is terrific in design. I can't say anything (per NDA) on the server side of things, but prepare to be wow'ed.
Anyhow, here is a list (from Microsoft) of the MS blogs that cover the Office 12 components. If you know of any others, please post them in the comments.
Microsoft® Office Access
What's New in Access 2007 (Eric Rucker)
Microsoft® Office Excel®
What's New in Excel 2007 (David Gainer)
Microsoft® Office FrontPage
What's New in FrontPage 2007 (Rob Mauceri)
Microsoft® Office OneNote®
A User-oriented View of OneNote 2007 (Chris Pratley)
OneNote General (Owen Braun)
Microsoft® Office Outlook®
Outlook General (Will Kennedy, GM)
Outlook Tasks and Time Management (Melissa MacBeth)
RSS/Search/Sharing (Michael Affronti)
Outlook Programmability (Ryan Gregg)
Microsoft® Office Project
What's New in Project 2007 (Dieter Zirkler)
Microsoft® Office Publisher
Publisher 2007, XPS and more (Jeff Bell)
What's New in Publisher 2007
Microsoft® Office Visio** **
Visio 2007 (Eric Rockey)
Microsoft® Office Word
What's New in Word 2007 (Joe Friend)
Microsoft® Windows SharePoint Services
Windows SharePoint Services (PJ Hough)
Document Management, Workflow, & Records Management (Rob Lefferts)
Office 2007 New User Interface
Office 2007 New User Interface (Jensen Harris)
Office 2007 New XML File Format
Office 2007 New XML File Format (Brian Jones)
Publishing XPS Documents
Publishing XPS Documents (Andy Simonds)
Publisher 2007, XPS and more (Jeff Bell)
PDF Support in Office 2007
PDF Support in Office 2007 (Cyndy Wessling)
TechTalk with Steven Sinofsky
TechTalk with Steven Sinofsky
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