InfoPath Super-PM Ned Friend has a post up regarding the upcoming InfoPath integration with Visual Studio Tools for Applications (VSTA):Visual Studio Tools for Applications : Microsoft Office InfoPath 2007 Beta integration with VSTA

What does this mean for the advanced InfoPath form designer? Well, if you're ready to write your business logic in C# or VB.Net, VSTA gives you an environment to do so without needing Visual Studio. Imagine the environment you've had in the past for writing JavaScript and VB.Script now ready, willing, and more than able to take on writing .NET business logic against InfoPath's new swanky managed OM.

The integration here includes passing on whether you're designing a rich client form or a form for the rich and the reach (web) environment, meaning that we ensure Intellisense only shows you the OM that you should be using (some client OM doesn't make sense when you're writing managed business logic for the server).

And if you're really interested in writing business logic for the reach forms (those rendered in IE and Firefox), you'll be writing against the new managed OM (sorry, no script business logic on the server).