I'd love to see Jeffery"s take on this too but unless he's into developing multi-lingual sites he's probably going to need guidance to as which method is Best Practice at the moment. Google rankings can change at any moment and I've seen a lot over the years about which method is better
xxx.domain.com or domain.com/xxx/ ;-)
However, If he just covered the above 2 methods then I'm pretty sure that most of use would be grateful :-)