>My question for these scenarios is whether this is worth and furthermore how you would actually use this thing.
>
>Since it's an ISAPI extension it pretty much means you can't use another ISAPI extension to generate the output such as ASP or Web Connection. Since XML is useful mostly in dynamic environments that whole concept goes out the window.
>
>But the concept is simple enough that this could actually be implemented server side with ASP or Web Connection by checking the browser and then doing the appropriate transforms on the server before returning the content.

>Am I missing something (without having looked at the document above <s>)

No you're not missing anything. For dynamic content, we could do this already by checking the user agent and deciding whether or not to transform on the server. Once your server classes do this by default with all returned XML output, you're covered. I think that XSL extension only fills the gap that we had for any static or prebuilt content that was being requested directly. For me, this isn't much of a gap.