Ive found converts for Babylon, Lingvo, Langenscheidt, and PWN (polish) formats. It seems mdictionary for symbian used plugins distributed in .sis files, no idea what format theyre in. the mdictionary project for earlier versions of maemo just used xdxf and stardict formats.

Do you have specific mdictionaries your particulary attached to? Have you looked at the available stardict dics? There used to be a bunch hosted on sorceforge, but they were taken down at some point. the cache exists with their exact file names, and with a bit of googling you can still find many great dics already in the format.

Oh, and I never had much luck with Qstardict. Would only recognize some of my dictionaries. Mstardict works with them all. Others experiences might vary.