Originally Posted by igorsk
Mobi does support UTF-8 (-unicode switch of mobigen). I'm pretty sure Kindle can read those, but it's possible that the bundled fonts do not have Greek characters.
Latin and Greek texts are of great interest to me, too, as you may have seen from some of my past postings.
Latin is no problem, but for ancient Greek you really need to use a format such as PDF which supports embedded fonts, and embed a suitable font into the document. Unicode supports modern Greek, but not the accents and breathing marks required for ancient Greek.
Mobi isn't a good choice of format for ancient Greek.