1) Go to www.imageshack.us
2) Upload your photo file and click "Host It" (don't enter in your email, or check any of the other options)
3) Copy the url called "Hotlink for Websits" (it's the third one from the bottom)
4) Paste this url into the body of your review.
This only works for reviews posted from the item page (the one with the formatting tools like bold, italics, etc.). It will not work from the Rate It! pop up window on the list pages.
I think that images can be especially helpful for travel reviews personally, but it will be neat to see how folks choose to use this feature.