XML Include sources

[tangent]

Does anyone know if it's possible to source xml via http or any method other than a local file? It would be extremely useful if you could specify a remote source like this.

<include>http://www.example.com/dynamic.xml</include>

I haven't actually tried this yet since I can't at the moment and I'm assuming it's currently impossible but thought I'd ask. Searching the forum and a google search doesn't turn up anything informative.