Why mirror a mediawiki?
Many important OERs are presented as a mediawiki site, including wikieducator.
Suppose you have developed resources on wikieducator, to use with your own students. So what happens if your connection goes for a week or a month? Of course there is the pdf printing service (which is great!), but what if didn't print, or you want your students to access the material online, and your international bandwidth doesn't support it?
Here is a software demonstrator http://www.ict4e.net/mirror/wikieducator/index.php
For example, here are two pages (measured with Yslow), one with a number of images, the other without significant images:
|mirror without images||mirror with images||original page|
|Page: Main Page||||||Main Page|
So at least it's a saving of 50%, but if you turn images off, you might save as much as a factor of 10 or more.
In Bjoern's view, this may well be a 'sweet spot' application: Very little code, very easy to install (if you have php), but gets you a good set of functionality (transfering data as needed). Of course a few more things would need to be done, such as caching of images, and some page names with special characters don't work yet.