A bunch of my friends will occasionally post pictures of their meals on facebook -- either because they're eating out somewhere particularly awesome or because they've cooked something themselves which they want everybody to see. I can't imagine anyone wanting to photograph everything they eat just for the sake of keeping track of it, though.

Definitely need an iPhone/Android/whatever app. Email is too much effort.

Also, a facebook app. Once food photos start showing up in my newsfeed with "Posted from eat.ly" under them, I might start checking it out.

I'd de-emphasise the "health" and "calorie counting" side of things and play up the "food porn" side of things. I don't want everybody to know about the boring healthy salad I had for lunch today, but I do for some reason want everybody to know about the delicious foie gras risotto I had at l'Atelier de Joel Robuchon the other night (as proven by the fact that I just found a way to brag about it in this very comment. nom nom nom)

Maybe provide a way to rate things by delicious-looking-ness? (You might want to think of a better word than delicious-looking-ness.) People could compete to have the most delicious-looking food on the entire site (like hotornot but without quite as much potential for ego shattering).