good question, but AFAIK? No.
OTOH, it will customize if you take time and use it careful. I'm from mainland europe and when I set Siri to US, it will recognize me most of the times. If it once did recognize me after a difficult sentence, it will learn from that and subsequent uses of those words are less of a problem.
If I'm in scotland, I need time to adapt and recognize their prenounciation, but Siri seems to need some TLC as well. And it's beta (I can't remember Apple putting out a beta?!) so it will collect a lot of data these days and get better all the time.