I'm sitting in a talk for Regional Directors in the Amsterdam RAI by BJ Holtgrewe, who is a lead developer evangelist at Microsoft. These are rough notes...

BJ says he was the best VB6 programmers in the world. ;-) Then, he went away to work at Microsoft Research for 3 years. Now he's working in the Visual Studio group.
The next version of VSTO is completely different from past releases. It’s all in Visual Studio.
Outlook plug-in tools were late comers to VS2005 plans.
Outlook has 4 object models (and that's not including OWA, is it? Managed extension adds a bit of complexity but a lot of additional capabilities.
Garbage collection is tricky, no matter how you look at it.
~75% of RDs in attendance have played with VSTO beta.
~6 germans, 4 french, and 10 others.

BJ showed the BofA/Korn Ferry International video wherein they build custom Outlook addins.

Allows third parties to aggregate disparate types of information about people inside Outlook.

People spend their lives in Outlook anyways.

Question: does this represent a shift away from SmartTags? Answer: No.

Demo: Outlook knows nothing about custom types like accounts, scorecards, sales opportunities (metadata).

CRM application: managed control (grid control) that allows users to sort emails by “account”.

Inbox

Accounts

Sent Items

Uses "Maestro" that works with SQL Server 2005 *Express*. SQL Server Reporting Services builds “scorecards” on the fly. Demo written in C#.

Question: Are you building tools for OWA and OMA?  Answer: No.

Offline support uses a local SQL Server Express database to persist changes until the user goes back online.

 

BJ made a point of defining where VSTO fits in the pantheon of VS SKUs and said that “we’re not doing a good job of talking about this, even internally. VSPro and VSTO are sister SKUs”

However, VSTO will not have source control integration (need to confirm!) whereas VSPro will.

The real diff is that in Visual Studio Professional, you can use C++, J# and the Compact Framework. The VSTO team figured, rightly, that there aren't too many Office developers out there who write C++ apps.

Both VSTO and VS Pro cost U$799 and U$199 companion pricing if you buy either one or the other.

Whitepaper to be published soon.

Resource: http://www.groktalk.net

Question: "What do you think of how we implemented this plug-in for Outlook?" -BJ
"It works if you document it well enough." -Anonymous Regional Director

In my humble opinion, Outlook plug-ins are tricky business. Outlook is a refined application with entrenched user expectations and subtle conventions that developers must follow to the tee to successfully extend the franchise. As a rough rule of thumb, if you can't drag and drop the things in your plug-in to and from other Outlook components, you might want to consider an alternative, like SmartTags.