While there, you could maybe take another look at my 'Self-iterating Objects' patch further down the same page. Having used this extensively myself over the last few years, I am more than ever convinced this is a worthwhile improvement.
Self-iterating objects is a handy patch, I like it as well.
But when you add it to 5.2, having both __iter and __pairs seems unnecessary and confusing. I think it would make more sense to unify the two. i.e., change the event name from "__iter" to "__pairs".