When I was facing Same Origin Policy problems while developing Bitcoin Pie, I was excited to discover how anyorigin.com solved the issue for me ... only, a week later it stopped working for some https sites.
Having recently discovered Heroku and Play! Framework, I found that deploying a simple server app is no longer a big deal, and so made out to develop a simple, open source alternative to Any Origin. Check out the project on github (it contains a nice demo of Play!'s asynch IO).
Usage is similar to anyorigin. For example, to fetch the data from http://google.com with jQuery, use this snippet:
$.getJSON('http://www.whateverorigin.org/get?url=' + encodeURIComponent('http://google.com') + '&callback=?', function(data){
alert(data.contents);
});