There might be a hack or two that would let you do that, but there's nothing "official".
However, you could put the lyrics into a .txt file and upload it to your notes section... it's not exactly what you're saying but it's a start.
Question for you iPod owners: do you make playlists? I know that sounds silly but I used to organize my music by genre, now I just make, like, a hip-hop playlist, a drum n' bass playlist, a rawk playlist, etc. etc.