Is there some kind of command-line operation that I can issue that would be equivalent to clicking "Save page" during an edit operation?
I'd also want some way to specify the "Edit summary" field and indicate if the operation is a minor edit. Hmm, there is also specifying my User name which, I assume, would be even trickier.
I've no idea what equivalents or bindings or whatever there are for EMACs, but all of the above can be done pretty easily with "libwww-perl". Essentially, you can control exactly what HTTP requests get sent, just like a browser would, and it will handle things like cookies for you quite happily (you just give it a text file to use as a "cookie jar" IIRC).
If the worst comes to the worst, it's not that hard to code HTTP requests by hand: it's all just plaintext, and forms are simply sent as part of the data (he says, fudging it bacause he's never coded anything that used POST requests yet); cookies are just sent as an extra header, so that's easy enough too, once you've gone through the login screen and acquired one.
You might want to have a look at the "livehttpheaders" mozilla extension, which allows you to see exactly what is being sent between the browser and the web server, in real time: watch what it does when you save / preview a change in a sandbox somewhere, and that's what you're code has to do. http://livehttpheaders.mozdev.org/index.html