I hate how Explorer.exe shell extensions are run in the same process, if one crashes, the whole shebang goes down with it. It would be much better, security-wise, for them to run as their own seperate process, and be remoted via COM+ as an out-of-process thing. Additionally, it would seem to me, offhand, that something like that would also offer much easier compatibility between 32-bit and 64-bit stuff, all you would need is the proper remoting stub functions and marshalling stuff. I'm no COM guru though.