Without throwing out a lot of arbitrary, wildly-speculative dates, the best I can say is that localization is slowly creeping up in priority. But there are no dates to report or even an estimate. There are proposals targeted for other languages, but they are created with the understanding that the menus and prompts will all be in English… for the time being.
A localized interface means that all the menus and prompts would be translated into other languages. It seems logical to crowd-source the translation to the communities creating the sites. We need a way to follow, and understand non-english-speaking communities. We also need to come up with methods where we can learn and understand the cultural issues which will likely be virtually unknown to us. We cannot assume a site is running smoothly simply because we cannot follow what is going on.
It's a big undertaking.
Quick update (August 2013):
We are actually working on localization.
ETA: still 6–8 arbitrary units of time.