Today, ICorDebug is not documented on MSDN, even though it’s a public API. Your best bet is a few random MSDN articles and some other scattered resources I list here.
In fact, search MSDN (as of Jun 6, '05) for “ICorDebugILFrame” and it comes up empty.
With Whidbey, we will finally get real documentation on MSDN. I’m excited. It also means I can finally include hyperlinks to ICorDebug interfaces when I talk about them in my blog.