Back in January, I came across a post by Arne Babenhauserheide on capturing images into Org . It looked interesting but required Image Magick, which doesn't play well with OS X. I thought at the time that it would be pretty easy to adapt but I never got around to it.
Then the other day, I came across this reddit post that pointed to a Stack Overflow post on the same question. That bit of code handles both the linux and OS X case so I thought I should install it and try it out. But then I saw a comment on the reddit post that pointed to abo-abo's org-download over on GitHub.
Abo-abo's code looks like it can be configured to handle Linux, OS X, or windows and it's available on Melpa. Coming from abo-abo, it's sure to receive any necessary updates so if you're looking for a nice utility to grab images and insert them into Org files, you should give it a look.