These are the current volunteers/interested people in particular language ports of Koha. Those below have merely expressed intent or interest, not all of them are current Koha developers! :)
Italian (warming up)
Zeno Tajoli [tajoli AT palazzoforti.com]
Marco Gaiarin [gaio AT sv.lnf.it]
Francesco Magnocavallo [francesesco at yahoo.it]
Portuguese (status?)
French (check fr.koha.org)
Paul Poulain [paul.poulain AT free.fr]
Nicolas Morin [nicolas.morin AT scd.uhp-nancy.fr]
Nathalie Fargier [nathalie.fargier AT univ-lyon2.fr]
Christophe Augias [c.augias AT bernheim.nc]
Laurence Porte [laurence.porte AT eurecom.fr]
Am鬩e Fontaine [ameliefontaine AT yahoo.ca]
Jean-Blaise Claivaz [Jean-Blaise.Claivaz AT adm.unige.ch]
Irma Birchall [irma AT calyx.net.au]
Pascale Nalon [pascale.nalon AT ensmp.fr]
German
Catalan
Spanish (working on it)
Danish (in progress)
Polish
The translation is available for version 2.0. Of all the strings that need translating 99% are translated. They certainly need further improvements. Volunteers welcome.
Ukrainian
Spanish (status?)
Enrique Ramos (chile) [coorpro AT terra.cl]
Cristian Cabezas (chile) [ccabezas AT confluencia.net]
Javier Diaz(argentina) [jdiaz AT siu.edu.ar]
Veronica Lencinas Cordoba, Argentina [vlencinas AT yahoo.com]
Bengali/Bangla (status?)
Chinese (traditional) - OPAC 100% complete, INTRANET 97% complete
Hindi (status?)