I think the answer is zero or nearly zero. If you have a bit of patience, I can do a port of tipa.sty (quite easy), but it will take some time before I can start on it. in the process taco and i can discuss low level support issues as well; it's all a matter of demand and time; of course after a port, taco would mildly force you to write an article for the MAPS -) I had done some basics with the font/encoding parts before. I solicited feedback on what next parts/features were important to tackle next, and I got nowhere. I'll try to dig this up and send it to you guys in the next few days. (Remind me if you don't hear from me!)
Perhaps this is a stupid question, but do we need more than some definitions in the Unicode encoding vectors and typescripts for some fonts? Is (T)IPA support about more than using some phonetic chars? Please enlighten me. Grüßlis vom Hraban! --- http://www.fiee.net/texnique/ http://contextgarden.net http://www.cacert.org (I'm an assurer)