Remember that Stack Overflow (in Portuguese) went through the same process as all other new sites in the SE network. It started as a proposal on Area51 and went through all the stages and is now in public beta.
This process guarantees that if there is a community large enough to generate enough good questions and answers it can launch, which is a fair process.
Personally I believe it is essential to leverage all available knowledge without language barriers. The language specific Stack Overflow sites do just that. It would be great to see interesting questions being raised and answers being given by people formerly unable to participate in the effective Q-and-A format of the SE-network. Interesting questions will migrate across language specific communities which is good and helps in getting answers in any language.
I'm looking forward to see the other language specific Stack Overflow launch, like:
I don't see a proposal yet for Stack Overflow in Chinese but that is a matter of time.