Recently I blogged a little on one aspect the VS tools for office. Here at the PDC I saw version 2, which comes with Whidbey. And it's a whole new ballgame. Behind the scenes there is still the office automation model, but they have done their best to hide that. Some VSTO 2 features:

• Build an Office app on a Word or Excel document inside VS.NET Whidbey
• Drop Winform controls on the (Office) document
• Embed an XML data island in the document
• Embed (or link) the assembly in the document template
• Program against real .net objects, with .net events
• Easely create smartpanes (the thing you get pressing F1 in Office 2003)
• Communicate with a backend using a webserver

You communicate with the contents of the sheet using just two classes, range and list. Range objects map to named ranges in the sheet and have very handy events, like onchanged. The best thing off all is that every reason for using VB.net instead of C# is gone (:>) to build the richests clients you can imagine.