I was waiting and waiting for this as well, but checked homebrew during RC6 and there was a PHP70-memcached, so I took that to mean it had finally caught up?
Yup, there are two, and they are entirely different.
One uses the historic library, the other uses the new library. Why they decided to do it this way is beyond me.
edit: never mind, I'm going to figure this out by using the internet!!