The 2007 Microsoft Office System has so much new functionality and so many new features that it's a bit intimidating. Where do you start learning?
You can download the beta, of course, and many people have done just that -- there were 500,000 downloads in the first two days it was available. But if you've been too busy to do that, or you can't install the beta for some reason (fascist IT policies, for example :-)), here are three links to help you get up to speed quickly on what's new in Office 2007:
2) For developer information about how to customize Office, the Office Developer Center is the place to start. There's a lot of great information there that has until recently only been available to developers under NDA in the Office early-adopter programs, but now everyone can learn the details of how to customize Office and how to integrate other applications with the 2007 Office System. The What's New section is a good place to start, and it also includes a comprehensive list of the most active blogs from the Office team.
3) MOSS (Microsoft Office Sharepoint Server) 2007 is a huge topic, especially now that Sharepoint has been consolidated with things like Content Management Server, Forms Server, and Excel Services. The Servers section of the Office Developer Center is a good place to start. Another interesting resource is the WssDemo site, where you can get a hands-on feel for how MOSS 2007 works. There's an interesting collection of MOSS 2007 screenshots on that site here.