Hi and thanks for your interest in my question!
Nope: I'm not the only one to contribute to this wiki.
I was thinking about something like MarsEdit (an app that does exactly what I ask, but only with blogs/wordpress).
You know: I began this wiki, and I want to populate it as much as possible in littlest time... that's why I wanted to use off-line time too.
OT note on MarsEdit: I contacted this app's support, as I was told that it could do the trick. They kindly answered me that their app doesn't "link" to wikis "out of the box", and that a good starting point (not a solution, I'm afraid) would be to know which kind of API I'm dealing with... I can choose among AtomPub, Blogger, Blosxcom, Conversant, MetaWeblog, Movable Type, WordPress API's... do you (or anyone else) know if MediaWiki sports any of these? Thanks!!!