The sessions for Microsoft's Professional Developer Conference (PDC) 2005 have been announced.  I'm really looking forward to it, I'll be the speaker for the hwnd/Win32 interop talk.  (Which is why I'm so anxious to finish the white paper -- so I can start work on the talk!)  Here's the official abstract for my talk:

Avalon: Integrating Avalon into Your Win32/MFC Application
Avalon is great for writing a completely new application, but what if you have an existing Win32/MFC code base? Learn how you can create mixed Win32-Avalon applications, both by putting Avalon content inside of Win32 HWNDs and by putting HWNDs inside Avalon content. See how to integrate Avalon into your DirectX applications (by using DirectX on an HWND).
Session Level(s): 300
Track(s): Presentation

Reminds me, I need to get that abstract updated with information about ActiveX.  Windows Forms interop is generally the best way to use ActiveX controls inside a larger Avalon application, but hwnd interop is the way to expose your Avalon logic as an ActiveX control.  So the first scenario is discussed in the Windows Forms interop talk, while that second scenario I'll be covering.

As always, I'd appreciate your input so I can make sure I talk about what you want to know!