It looks great, but I can't help but feeling that the left on the left side is just way too huge. From what I recall of seeing images of lemons the leaves on a lemon branch aren't usually the same size as the lemon itself.. or are they? Either the leaf looks much too large, or you could move the lemon over to the left a bit. In any case, the leaf competes for my attention against the lemon itself. I'm not sure what you're trying to have the focus of the icon be, though.

While it's not detrimental to the piece, is there a reason why you chose such pale colors? (I'm not sure if that's the correct terminology for what I'm trying to say). when I think of a lemon I think of vibrant yellow (and a more vibrant green, if leaves are involved).

Also, the shape is nice and lemon like, but what about making the nub on the end stick out just a little more? I think it would help make the overall shape look a bit more lemon like. If you look at it for long enough it starts to look like an egg.

If you're using Mac OS X (which I doubt seeing how many replies suggest MSPaint-- it looks like the majority of you guys are on Windows machines) you definitely want to check out Pixen: http://opensword.org/Pixen/ It's awesome.