There is one wonderful post that I think everyone should read - Two Men and a Little Farm that shows just how drastically our food supplies have changed in the past century, especially the heirloom varieties. The numbers are astounding! This is exactly why I plant only heirlooms and not hybrids - so I can keep the seed cycle and preserve them for later use.
Btw, those pictures of heirloom tomatoes and eggplants are amazing! I'm not going to have too many varieties of eggplants but I really do hope that my basket of tomatoes in August will be just as beautiful as that picture.