I listen to a lot of music pdocasts & would like to add the song titles in the lyrics field so I can display when playing on my Nokia N8. The mad thing is I've already successfully done this once using a previous version of mp3tag but for the life of me can't work out how I did it, has something changed?

there's a field called UNSYNCEDLYRICS that itunes populates when you add the lyrics through itunes, but I've tried this on other podcasts & it doesn't make it into the music player on my when I copy the file across, so I must've used another filed.

Any ideas?

There are several problems: one: iTunes does not always save the data in the tags but keeps it in its database. So when you use a different program then that reads only the tags but not itunes's database ...
I think the field UNSYNCEDLYRICS is correct.
You can check if you have used other fields (like LYRICS) in the extended tags dialogue - Press Alt-T for that and check what fields are in the selected files.

Please note: you have to preceed the lyrics by a language token and two pipe symbols, e.g.:
eng||We all live in a yellow submarine

You can make that universal by adding (literally) xxx for the language token as this means "any language":
xxx||We all live in a yellow submarine
I hope, it helps.