I came across an interesting forum post by Suzanne Cook today.  Here's what she had to say about 1.1 assemblies and 2.0 assemblies in the same process:

As of today, only one version of the runtime is loaded per process, no matter which versions of assemblies are later requested.  So, if the v2 CLR is already loaded, it will successfully load a v1 assembly and run it against the v2 CLR (not the v1 CLR) without reloading the already-loaded v2 CLR .dlls.

While we're on this topic, you may want to check out http://blogs.msdn.com/suzcook/archive/2005/01/26/361092.aspx for related compatibility information.

One of the primary drawbacks to the 2.0 WebBrowser is that it doesn't seem to be as flexible as importing the ActiveX control directly.  However, Microsoft anticipated this and created a way to hook into the WB to make it as flexible as you like.  See the discussion here:

http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=7228&SiteID=1

This is old news, but here is a very informative article I just now ran across:

Robert Gelb's Top 10 .NET Tips and Tricks (http://www.vbrad.com/article.aspx?id=66)

I ran across an interesting KB article today.  I had never seen the "::" notation in JavaScript before, but here it is:

function ctrl::ClickEvent(a,b)
{
   alert("MyWindowControl_ClickEvent");
}

This function will handle the "ClickEvent" .NET event that is exposed to script through an object tag:

    <OBJECT id="ctrl" classid="YourDllName.dll#ActiveXSourcing.MyWindowControl">
    </OBJECT>

For more, read KB313891

Note to self:  the January 2006 release of the MSDN library does not contain VS 2005 documentation.  You have to install "MSDN Library for Visual Studio 2005"!