We've set up a wiki at perl.org.br to write new articles and translate documentation.

The interesting part is that we wrote a TWiki plugin to accept POD instead of wiki-markup or html, so we just published perldoc and allowed people to translate it; all the changes can be reviewed using version control and other TWiki features. (TWiki itself is written in Perl :-)).

And I think that helped the project to be successful, given the number of registered users and translated files.

BTW - I'd love to collaborate with other user groups to set up similar wikis.