The first alpha version for the next major PHP release was made available last week. A list of the new features is available at php.net
To make it widely available and let people with OS X easily test their code against that new release, it's now already available on php-osx.liip.ch
Go, get it and test your applications, and submit bug reports, if you hit something suspicious. This will help to make PHP 5.6.0 a stable release some time in the next months.
I couldn't manage to get phpdbg compiled, therefore it's not available yet. I didn't try hard, will try again in the next release.