I'm quite alright with someone posting in their native language, but I would request two things:

1. Realization on the part of the poster that they are less likely to get help, as the post can only be understood by a segment of the Monestary.
2. Either a link to a translation (e.g. for the parent node, a link like English by Google

The former is mostly unenforceable, but the latter could be handled through janitorial/consideration -- and maybe even helped by the pmdevils (which I'm still trying to become a member of, I think vroom gets too many private messages!) implementing something like an [português->english] "tag" that would auto-link to an English translation of the current node.

Now, the real question: as much as I think it would be nifty to let people post in their native language, is the additional work and reduced possibility of assistance worth it?