Excellent article on COM+ Callable Wrappers (CCW) in .NET
A couple years ago I spent time developing BizTalk 2002 AIC components with C#/.NET Framework v1.1 and learned tons about COM+ interop. I always planned to go blog about the basics and various tips and tricks for composing your COM interfaces, but after stumbling across this article, I'll happily point people to it on Peter van Ooijen's blog instead.
Obviously there is much more to learn than this, but its a nice simple primer for people new to COM+ development. Now all I need to do is find a blog post on controling COM+ transactions, Object Pooling, and other higher-end topics so I don't have to blog them either.