Not to whizz in anyone's cornflakes here, and we're happy the 37 signals guys have come around, but StackOverflow Careers has had remote specific job listings for a really long time. If you're interested we keep a decent number of them running pretty much all the time http://careers.stackoverflow.com/jobs?allowsremote=true
South Africa. My first guess was that my results were being filtered by location, but if so there's no visiblility of this restriction and the posting does state:
"We’re looking to hire the best people wherever they are in the world."
I found the posting from the OP's link, BTW; if this is indeed the issue, it looks like careers.so ought to apply viewing restrictions equivalent to the search restrictions, otherwise cross-posts to other job sites are going to confuse other people in the same way it did me.
Yes. All the differences here are due to employers choosing where they want to advertise their jobs. We have 7 granular advertising regions for employers to choose from. You can see them at the bottom of the post job page.