Well, what I meant was something like this:
Where the 45-degree line moves over a pixel and makes a double pixel, that's where the aa really kicks in: it's an angled gradient that fades the original position of the line into the background while the moved line goes on next to it, creating a smooth curve. I tried to show how it works with an example in greyscale and then a "exploded view" that shows how the aa is a collection of gradient-shaded lines.
MoD, you could show me what you mean, I have an idea, but I just want clafrification. Thanks man.
SinX, the colors are awesome. I don't know shit about AA (it looks fine to me), so I'll leave that to the veterans.
The aa is good, EXCEPT for the veins in the middle of the leaves. You merely surround the lines there with colors between the line and leaf color. Instead, you should only go for about 50% of the length of the diagonal section, away from the 2px touching bit. I could show you what I mean if I'm not clear. Otherwise, pretty ace job; good design and colors.